Yes the valve service will most likely involve removing the cams, so the belts will be off anyway. That is, if they need to change any closing shims. So replacing the belts shouldn't really cost any more in labour than getting the valve clearances adjusted.
And worth fitting the factory original belts in my view. Just the odd failure of non-original belts coming to light..
I still prefer to reset the tension on new belts after about 1,000 kms (600 mi), even though they have streamlined the maintenance intervals in an attempt to leave them for longer. They 'settle in' in a way which is not really safe to over-tension them to avoid.
The recommended tension of 110 Hz is actually a bit tight. Better to set them to 100 Hz and re-check them. Whenever I check them at the 'recommended interval' of 12,000 kms (7,500 mi) they are loose as.
So ideally you should set them to 100 Hz, re-check them at 1,000 kms, and again at 6,000 kms. Otherwise they spend half their life running too loose, which is bad for the belts and your cam timing. This way your belts should last longer, and your bike will run better.
And welcome to the forum, and the wonderful world of Ducati superbikes.