Mercury for a gravel event?

[JimK]

I never experienced instantaneous shifting with my Rohloff because of the need to back off the power to shift down, which in turn lost me a lot of momentum, 

Perhaps the difference in experience is due to a difference in conditions, in particular a difference in speed/momentum.

My experience with derailleurs is that the system has a delicate phase while the chain is moving from one sprocket or chainring to the next. I would estimate that this delicate phase is about a quarter of a wheel turn for a rear shift and similarly a quarter turn of the pedals up front. The temporal duration of this delicate phase will then depend on how fast you are going! And, for a front shift, what gear you start in.

I think for a Rohloff the time for a shift is pretty much independent of speed. The mechanism inside has to settle down and maybe that takes a quarter second or thereabouts.

So anyway my hypothesis is that the Rohloff shifts faster if you are going very slowly, while a derailleur shifts faster if you are going very fast. I am usually going very slowly, so the Rohloff suits my style!

[Relayer]

I think your hypothesis sounds very reasonable Jim, and to be fair mikeg did mention gear changes when riding slowly.

The mention of rapid changes in gradient led me to think of lots of undulations where I like to tackle shortish climbs out of the saddle, which is where the need for momentum comes in. If it is a longer climb then yes, I can see what's coming and settle into the saddle, get into low gears at the start and pedal up at a steady sustainable speed, in which case the Rohloff is fine and dandy ... apart from maybe the pepper grinding 

Jim

[mickeg]

...
I never experienced instantaneous shifting with my Rohloff because of the need to back off the power to shift down, which in turn lost me a lot of momentum, which then necessitated more downshifts. 

With derailleurs I can keep the power on and better maintain momentum ...

I learned how to ride a bike as a kid with first a single speed, then a Sturmey Archer three speed.  Later switched to a non-indexed bike that at that time was called a ten speed (five speed cluster in back, two chainrings up front).  The ten speeds back then did not have any ramps and pins to aid shifting, and friction shifting was best done with a degree of finesse.

Bottom line, on every bike I rode for decades before I had an indexed shifting bike I had to back off on the power before shifting, especially the front derailleur.  When I built up my first indexed bike a bit over a decade ago, it never occurred to me that I should pedal hard while shifting, so I did not change my style. 

My foldup bike even mixes both worlds, it has a Sram Dual Drive internally geared hub and an eight speed cassette on it. 

I always back off on the power before shifting on every bike.