I have a VM with MC running on my unraid server and never have any resource contention issues even using MadVR or SACD rips, but I imagine would be different story if an appliance NAS with lower end hardware in them.
Sure, if you're going to use MC for it's full range of features, like higher-end encodings or resolutions then you'd absolutely want to consider making certain it has plenty of resources at it's disposal. Running inside a VM definitely presents the potential for interruptions that you might not get on dedicated hardware, that's absolutely correct.
To that end I've got an i7-equipped NAS with 32gb of RAM in it. It's definitely not under-powered and having it run an MC install for the arguably limited number of functions I want out of it is pretty likely to avoid any VM-based problems.
I don't want to take a side for/against using a NAS. My thought is if you're really pushing the full range of MC features then you'd be a fool to avoid using a dedicated piece of hardware for it. I'm not, so I'm willing to entertain the idea. But not if it's known to be a clusterf*ck of incompatibilities. Been there, done that, don't want to waste that time again.
Likewise, lashing up a combination of media stored on the NAS and MC installed on a dedicated box is probably not beyond the realm of considering. It just adds yet another lump of hardware and the 'glue' to stitch it together. Fortunately it's a pretty cheap piece of hardware, so cost alone is not really much of a factor.
QNAP and things running directly,
sigh, their support for this is
somewhat erratic. Yeah, it '
ought to be possible' but I'd rather suffer the slight performance bump of running inside a VM instead, given I'm really only using it for music management and not all the other fantastic features.