Interesting how much he liked the Digitech GNX. I've been raving about the GNX for some time now as a lone voice in the (POD, VoX) wilderness........ I FAR prefer it to the pod xt, TLSE, and the Boss's, though I've not heard the GT8 yet. A used GNX2 is the deal of the century. I now own 3 GNXs. I keep one parked at each of my two band's studios, and one at home. All that said, I only use them in tube amp series loops for effects/vol/wah. But I consider them a backup as I carry a power amp and lead pedals so if my tube amp goes south, I can slip into a clean model, run it into a power amp and into the (separated) speaker of my 'real' amp. Very flexible and terrific sound. Also, I only use clean models on the GNX, as I prefer to use my favorite lead pedals for lead tones.
Hey Nick, bear in mind that none of mine are the 3000 - I have the 2 and the 3 but the technology is the same. Just some feature differences. All of them are firmware upgradeable so the specifics of any sound are 'probably' comparable.
I had pods up through the XT bean, and the others I mentioned, for years. I also used the GNX2 as a modeler straight into a powered monitor for awhile and really liked it - prefered it to the POD, etc. Plus, it's way more affordable, esp used, has a small footprint, and is just very user friendly. Please bear in mind though - if you want to use it just for modeling to a board or powered speaker system - I pretty much confined my use to a variety of clean patches, preferring to get my best lead tones from my pedals (V-Stack, OCD, BB, etc). But I gotta say, that review at thestompbox.net confirmed all my impressions.
Unless you really want to record with the pedal, skip the 3 or 4 and just get a 2, or the 3000, I suppose. I haven't examined, or played the 3000 but the 2 is great and again, a terrific deal used.
Nick, you have to be careful using a stomp box model for boost IN A LOOP. The dynamics are a bit different than when it's in front of an amp. That said, I use one of them for a slight boost (I'm trying to remember which........ mmm.. it's either the 250 or sparkledrive) setting the gain quite low and the overall effect higher for a minimally colored volume boost. Any other more significant tone altering boost would probably be best in front of the amp (any number of lead pedals with gain low, or a COT50, etc). You DON'T want to slam the amp's output section with a large loop boost.