I don't think is so hard to have a decent live sound with Pod hd500
the first thing is to try to reproduce the sounds in your head of real amps that you had dial in the past
For example, during many years i played a jcm 800 modded so when i started to dial with the pod , this was my base to reproduced that real sound in Frfr..
So the "plexi" was the best for what i seraching for , after i make a screamer for more sustain and ...etc .. step by step :-)
I think to approche real sound you have to cut some bass (120hz) and bright (presence) (6khz)
in real amps + real cabs with mics you don't have so many low bass and harsh bright
You have to boost med (700hz) because modelisation didn't have anymore medium
The problem with all modelisation processors is tweakin, tweaking, tweakin duurrinngg maaannnyy timmmeeee !!! :-)
Here is an example of what i did with the POD HD500 in Frfr :
Good Luck :-)
Bertrand