Evil sovereign-
The new frame will take a 29×3 on a thinner rim but if you were going to run 29, especially in the winter, it will still work best with a 2.4, there’s plenty more clearance on the new frames, so the tyre in Spectabilis’ picture will fit without problems (sorry Spectabilis 🙁
As for 650+, if you enjoy hooning down technical singletrack and hopping off and over things then its great, it does really good things to the bike’s handling and flickability, just feels a bit more hooligan – but if your riding is more long day in the saddle then the 29er probably wins. The Stooge geometry is designed to have a slightly larger front tyre so if you were running B+ i’d recommend either a 3.25 front/3 rear or a 3/2.8 combo,though i guess it wouldn’t be that important.
From experience, a 2.8 on a 30mm rim spins up lovely, feels really light, a 3.25 feels a lot more draggy. If you’re going to run a 40mm plus rim on the back, make the 3.00 your largest back tyre.
Hope that helps. Have a word with Charlie too 🙂