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Biker friends think I'm daft having disc at the back and V at the front, but if ...
Two and a half years ago I bought a titanium touring frame. Was not really looking for one at the time, but I had always wanted a titanium bike so when i saw the frame at a fantastic price, I went for it. That frame takes disc only, not rim brakes. If I bought the front fork that went with it, that would have cost another $325 USD. But I had a rim brake fork in storage that had the right dimensions (fork rake and the crown race to axle length) to fit nearly perfectly, so decided to save the $325 and use the fork I already owned. Plus, I did not need to spend the money on a new disc unit for the front, but already had the rim brakes I could use, that saved close to another $100 USD. Thus, total savings was over $400 USD.
Almost nobody even notices that I have V brakes with a travel agent on the front and disc brake in the rear. But I used the same rims on the front and rear, so the disc wheel has the machined rim brake surface so that might help hid the difference in brakes.
And if anyone notices and asks, I just tell them that I saved a lot of money by using a fork that I already had when I bought the frame. And then I tell them that in my opinion, I would do it again as having a disc up front was not worth an extra $400 USD that it would have cost me.
When it is raining, the disc works much better than the rim brake, but when it is dry out the disc and rim brake are close to comparable. It is a touring bike and I have used it with a load of camping gear in four panniers. And touring bikes need good brakes. I am using Koolstop Salmon pads on the front rim brake which provide very good grip. Initially, the disc brake worked poorly compared to the rim brake, but I took the semi-metalic pads off the disc unit and put some cheap resin pads on, those resin pads might not last as long but they have much better grip. I now have great braking both front and rear.
In my case, it is not a Rohloff bike, so mine uses conventional six bolt disc, etc. In your case, putting the disc on the back means a disc brake unit, a Rohloff disc (is that four bolts?), and the Rohloff with the disc mount fitted to it, each of those things push the price up a bit higher.
In my case I am using drop bars with normal drop bar cable pull and I am using V brakes. There is a gizmo called a Travel Agent that can convert the cable pull for mixing standard brake levers with V brakes. I do not know if SJS uses them, but if you go with drop bars you should discuss the brake lever issues. I think that Travel Agents are no longer produced, but copies of them are made in Asia. But if you use upright bars with longer cable pull levers, then no problem.