Stellar, I just got a Power Engine 60 last Sunday.
I don't have enough experience with it to offer a ton of advice, but, so far, using JamUp through the unit, I leave all amp and cab modeling on.
It sounds really good. It may not be a proper guitar amp, but it pushes like one, let me tell you. It does sound different from running through a P.A. but not hugely so... a little less ultra-top end and a bit more push in the mid-range, I suppose.
I haven't tried it yet with my (semi-retired) 11R, but since I've had similar experiences with both the 11R and JamUp through various amps and P.A.'s, I'd say it would sound similarly good.