Well... for ambient sounds like pads and ambiences, and also some sounds with a long ring-out, 16 voices is important in my opinion... otherwise you'd be set up with nothing but organ-type "on/off" like sounds to work with... maybe this is what some users need only, but in my case there sure as h*** is no way around long release times.
Simple emulations of bells and plucked sounds also have long release times, and every time I use a layered voice on my 16voice REV2, I hear the voice stealing... it's rather obvious.
There is a way to make voice stealing harder to hear on any polysynth, no matter how many voices, but Sequential do not support that voice allocation method in their synths... it's a simple mode, where every time you hit a note, that was hit previously, and is still sounding, then that exact voice is retriggered, instead of triggering a new voice that would steal another voice with a different pitch...
That allocation method makes note stealing harder to notice, and at the same time it mimics how a lot of real instruments work (if you pluck an already sounding guitar string again, you do not get two overlapping string sounds, that string is simply retriggered)...
I've talked about Sequential creating support for that playing style in here before... and with an 8-voice synth this method really has some benefits voice-wise.
The Novation - PEAK has exactly this feature, and I love it for it...
and some ideas on how to overcome voice stealing:
One that I often use is to simply make the release times shorter... it's basically the only way to fix it... and instead (if I want more "tail" in the sound), I simply use either reverb or delay to mimic the release...