I've had a BMC AC01 with the Alfine 11 and belt drive for a little while now and have been getting bad pains in my hands. After doing a little research it might be pressure on my ulnar nerve. So I moved the stem up, lowered the saddle a little and tilted the nose up slightly. This has made an improvement in that it is not hard sharp pain any longer, more of a mild irritating ache now.

We also live in an area which has some rather steep, but short, hills and I do wonder if the extra weight (10.6kg) and hub gear of the BMC might be making it more difficult than necessary to climb these. Although the low gear is about equivalent to a 34:32.

I'm also starting worry that as my rides get longer the chance of a tyre getting punctured increases and the rear wheel is not possible to get off without a 15mm spanner.

The hoods on a drop bar do not seem to cause the pain in my hands so I'm thinking about changing bikes. Does this sound like a reasonable decision given the above?

I'm considering something like the Cube Attain:
Cube Attain GTC Race Road Bike 2017 | Chain Reaction Cycles

I would, of course, be losing the very clean and quiet belt drive of the BMC.