DigiTech GNX Series: Product comparison
We've heard and seen it all - GNX3, GNX4, GNX3000. What is the difference? More importantly, will it make a difference to you personally?
That's a difficult question to answer, but depending on your situation and preferred usage, the answer may actually exist! GNX3 and 4, for example, provide an onboard recorder and built-in looper. Do you really need that? Well, it is pretty easy to use, and lets you record your riffs on the spot - always (so long as you have a big enough memory card). However, if you're into PC recording, you may not need that - in which case GNX3000 will probably be a better choice for you.
The main thing to consider is that GNX3000 has the "next-generation" amp/cabinet modeling from DigiTech. This is not just hot air, and you can in fact tell a major difference between stock amp models on GNX4 and GNX3000. Whereas there wasn't much difference from GNX3 to GNX4, GNX3k really raises the bar. This is not to say that you can't tweak the other two units to sound comparably good - many people have done so, most notably Guitar3456. It's important to remember that, while GNX3000 may be the wave of the future, all GNX series processors allow customizing amps until you're blue in the face, and great results are actually possible (contrary to what the Guitar Center salespeople may tell you).
So anyway, here's a chart I put together that outlines the major differences between GNX3, GNX4, and GNX3000. Also, some similarities are listed. Find the features that you're most interested in, and see each unit's user manual for more information. After all, it's important to make sure that these things can, in fact, do what you want them to!
(note: this is a PDF file, I would recommend using right-click/save combination for viewing).
Comparison of GNX units