Just an aside. I've changed my Brooks B17 ( with some reluctance ) for a Sella SMP TRK ( size large although I'm not) I changed it because the Sella has a cut out and drooped nose; much easier on the pudental nerve. In doing so I lose a little 'thigh control' but I can live with that.

I built a derailleur bike with drops and definitely feel slightly happier when fighting headwinds. My Rohloff bike has been gathering dust pending a bar conversion. ... another sticking point in the conversion is that I now would also want hydraulic brakes.

The best hydraulic pedal bike brakes, in my opinion of course, are the Magura Rim Hydraulic Brakes, among other reasons because they clamp the largest possible disc, the rim of the wheel, so the discs run pretty cool even in urban rush our traffic.

But the rim hydraulics are fully self-contained from handle through tube to the caliper bodies, oil included, service-free for life (another superb feature); however, you need to be brave to try modifying them, because if you cause a leak, your investment is toast.*

I'm talking here about the HSxx series, of which I have experience of the most junior member, the HS11 deliberately chosen precisely because it provides less clamping force to begin with, and therefore less sudden, more controllable stops while for practical purposes the clamping force is well able to stop even a heavily loaded bike and heavy rider in an amazingly short distance without any of the drama of locked brakes that would accompany the maxed-out brakes the cafe racers brag about.

Unfortunately today the HS11 and the HS33 have the same amount of fluid in them to be compressed (which corresponds roughly to the size of the chamber in the more common type of wheel centre hydraulic brakes) and the only difference between them is that the cheaper -11 has attractive colored trim covers available while the -33 is monocoloured a nasty grey, supposed to look 'professional'. I also vaguely remember different handle lengths at least theoretically available to make fitting on busy handlebars easier.

The last time I looked, because some idiot opined that real bicyclists fit the racing versions, there was an HS22, available to fit drop handlebars, and there was a real racing version above the others which very likely fitted only on drops.

The racing versions come  with progressively smaller chambers and thus higher clamping pressures, at the cost of less nuanced control capability. If you choose the Rim Hydraulics, and have to take a racing version to fit drops, learn to brake with one finger, like the MotoGP racers atop 200bhp machines, approaching a tight hairpin at 230mph.


One more consideration. Though I'm a hard but not harsh braker at the T junctions at the bottom of steep hills, I don't brake often and I'm certainly not a comfort braker. Besides, I ride on general clean tarmac lanes. Despite all that, which you would think should give me impressive rim mileage, with only 11K plus kilometers on the rims, there is visible wear. Either my rims are soft aluminum, or the HS11 Maguras are still too much brakes for my environment and riding style, or Magura's own brake blocks, which do last a long time, are unnecessarily abrasive. Though not all that important to me except for hating waste, for a commuter that could easily become a cost consideration.

*I bought the biggest Service Kit, which is actually a total rebuilding kit, consisting of enough oil, tubing, olives (they fit inside the junctions tube to metal parts), whatever is necessary to fully rebuild one brake, because I knew I would be moving the handlebar up quite a long way even on a 59cm virtual top tube bike I had bought sight unseen, and feared the standard tube wouldn't be long enough, but it turned out to be just long enough, so the kit is unused. Today I wouldn't buy the expensive service/rebuilding kit, I'd just get a competent specialist to supply a new brake set on which he had already extended the tube length.

...
...   My Rohloff bike has been gathering dust pending a bar conversion....

When that conversion is complete, we need photos and some text on what you like about it.  And whether or not you would do anything different next time.

I am fully content with the brakes that I have.  That said, in rain I sometimes wish that my rim brakes were better than they are.

But I can't imagine trying to pedal into a strong headwind on flat bars on a long tour, thus I really wanted drop bars.  And I am happy with my choice.  I recognize that I am only a few percent more aerodynamic with the drop bars, but in a strong headwind I want every advantage I can get.

A headwind was the trigger for me deciding to change from flat bars to drop bars. I couldn't keep up with a friend who had drop bars and felt that the greater wind resistance provided by flat bars was a factor so I built a derailleur bike with drops and definitely feel slightly happier when fighting headwinds. My Rohloff bike has been gathering dust pending a bar conversion. I got as far as buying a pair of Sram cable brifters which can be modified to work with the Gebla Rohbox. The Hubbub adaptor is another option but another sticking point in the conversion is that I now would also want hydraulic brakes.

...
2. Not relevant to the Sherpa but the Rohloff twist shifter on the drop bar conversion was placed on a short Thorn accessory  T-bar fitted to the fork steerer column below the handlebar stem. I feel safer having the Rohloff twist shifter closer to hand on straight bars within easy reach for rapid shifting without having to take my hand off the handlebars.
...

It probably has been a few years since I mentioned on this forum why I have drop bars on my Nomad Mk II.  I am well aware that Thorn feels that the Nomad Mk II would be best with flat bars, that is why they did not sell the Nomad Mk II in an S size.  But I can't imagine trying to pedal into a strong headwind on flat bars on a long tour, thus I really wanted drop bars.  And I am happy with my choice.  I recognize that I am only a few percent more aerodynamic with the drop bars, but in a strong headwind I want every advantage I can get.

I tried placing the Rohloff shifter in several locations, but eventually came to the same conclusion you did.  I use the Hubbub Adapter that puts my shifter on the end of the handlebar.  That way if I am on difficult terrain where I want to have both hands on the handlebar, and also be able to shift, that location is the most logical.  Photo attached.

There have been many times when I was happy I could keep both hands on the handlebar for steering while I was able to simultaneously shift too.