Which reverb is better? I have a FireworX and am considering an M3000 if the reverb is really better.
Although the units have the same A/D & D/A converters, the reverb is definitely better in the M3000.
Think of it this way: the 2 units have the same DSP (processing power) available. In the FireworX this is used for several different simultaneous effects, whereas the M3000 only runs 2 at a time, or 1 when the engines are stereo linked - so, there's more power avaliable for the reverb algorithms alone in the M3000.
Since reverb is one of the most DSP demanding effects in general, there's a lot of DSP to be gained from reducing the reverb quality slightly, which is what we usually do in units that run many effects simultaneously - like the FireworX. In other words, if you want the best reverb avaliable, you should go for a dedicated reverb unit (like the M3000).
Or, you could consider the M-One XL, although this unit is in another price range. This is primarily due to the quality of the A/D & D/A converters, which is significantly higher in the M3000, as are the number of adjustable parameters in the user interface.
Except for TC System 6000 / Reverb6000 / Reverb4000, the M3000 is the most advanced reverb, in terms of sound & adjustability, that TC has to offer.