I'm running Flows & 2.35" Nevegals on my 'Trail' bike and 355's and 2.1" Nevs on my XC bike. I weigh about 13.5 stone and am a reasonably aggressive/clumsy rider. Have been very impressed with the 355's, stiff and strong, and relatively wide – 2.1 tyres plump up well on 'em. Light enough for the bike to have a real zippy feel. I've wrenched 'em around a bit and they're still true.
The Flow wheels definately feel stiffer though, and they really give 'fat' tyres a good foundation. I run 20 to 25psi tubeless (Stan's) and don't get much rolling of the tyre on the rim. They're also very confidence inspiring through rock gardens. Only drawback is that, compared to 355's, they take a little bit more effort to accelerate up to speed (but they're def not porkers by any means).
Personally, I think for the type of riding & bike you mention, I'd go with the Flows and stick some nice fatties on 🙂