My computer configuration is as follows: A Macbook (2.2ghz, 4gb Ram, 120 HD), Presonus Firepod/Firebox Interface and Logic Pro 8. So far, the plugin has worked flawlessly with this configuration. As for performance, the FM8 certainly doesn't bog down my computer, not with 4 gigs of Ram, which I suggest for all whose computer can accept that much. The patches change quickly and the sound is fantastic so I give it a 10 or 10 for performance. As I stated before, no crashes or glitches so far. Native Instruments have given me no trouble in the past and continue to perform that way.
I have been using FM8 for roughly 6 months. What I like about it the most is the excellent sound patches (presets and the custom stuff I have made). They are so full and lush that it makes me not regret selling off all my hardware synths. What I don't like about this plugin (as with most Native Instrument products) is its sometimes confusing look. I feel like Native Instruments could learn a thing or two from Logic ( designers about plugin layouts. I have lots of synth plugins (such as Abysynth, Massive, all of Logic's synths, Sugarbytes, Arturia stuff, IK mulimedia stuff) and this one keeps popping its head up on the top list. The samples are just so...I don't know, delicious might be the right word. I got this in a package deal which is the way to go. Buying these plugins individually is way more money. I think I got 4 plugins (FM8, Pro 53, Abysnth and Kontakt) for somewhere around $400. Its a decent chunk of change, but all those plugins have certainly seen there fair share of use. Yes, I would definitely buy FM8 again. It never disappoints.