i've read that the pod's DSP is actually quite high compared to similar products available in the market right now. the only down side (which can be a plus point, depending if you look at glass half-full / half-emtpy crap) is that the alglorithms for the effects in the HD are too zai already, such that they require waay more processing power than previous gen pods and other floor units.
so plus point is, damn realisitc amp emulation, high quality effects but downside is, you can't load too many of these unlike previous pods as you'll hit the dsp ceiling.
i've always relied on dual amps since pod x3 days and now i'm getting used to the dsp thing. my patches are usually quite simple, with 2 amps, 2 delays, one reverb, one compressor. sometimes i remove one delay for the smart harmoniser. i make do with dual amps like that cause i don't play around with 8 delays / reverbs. for more lushious patches, i usually just scale down to one amp but separate the left and right channels by 50ms by a digital delay and an EQ to recreate the dual track feel. it's almost like dual amps cause of the EQ.
i've had 1st hand experience with the gt-10, zoom g2.1 and ax3000. they all sound great, but none responds like a tube amp like the pod hd. for the price of around $700, the pod hd 500 is a
steal.
wait till you get hooked in this modelling gear thingy and you'll be talking about 11rack and axefx rack units, $1.2k and $3k plus stuff.
you can get more info about pod hd here
http://www.thegearpage.net/board/forumdisplay.php?f=53
but you needa filter through a whole lot of information cause it's shared space with axefx and 11r users