Well... I never really used feedback when I had both Mopho and Tetra, and my P08 does not have that feature... I've not used it on P12 either... so I cannot really participate in the debate.... but... I've been trying to use it quite a bit on the Tempest, simply because I hate the fact that the analog distortion on Tempest is global, and not per voice.
So I've tried to use feedback for a distortion like sound on a voice basis, and learned a few truths about that kind of feedback. First, if it's used on a self oscillating filter only (for kick drums especialy), it sounds like s***... a total mud-ferno... not even worth using in the slightest.... but used on oscillators it sounds really good and distorted... only bummer is that the oscillators on Tempest is rather inconsistent in the transients, so that sort of like erase that use of the feedback parameter (in addition to a few other Tempest feedback truths).
On synth sounds, I've only used it a couple of times, on Poly Evolver... for making plucked physical modelling style sounds with the tuned feedback... takes some tweaking, but it's definitely doable.
Regarding Mopho specificaly, I do NOT like the fact, that the feedback parameter is not a parameter in a preset... I like the Tetra better in that respect... I hate it when synths do not support preset storage of ALL sound parameters, and it's usualy a deal breaker for me... just like with Waldorf Rocket... Resonance is not storable, so no Rocket for me
