Another update: I have decided that I simply don't want to use the amp models in this thing at all....at least not yet. The Boogie DC-5 combo has excellent tone, clean or dirty, so I am basically using it as my 'amp model' haha.
AFAIC: Amp modeling is nothing more than a fancy word for EQ Settings. When you model an amp, and then plug it into another amp, each one is going to color the sound (unless you plug your modeler into a PA or other transparent amplification device). Why bother fighting one EQ with another? It just sucks the tone right out. Screw the 'Preamps' in this thing, they just mess up a good tone IMO.
I am using the GT-8 as an effects device. The new switch I made allows me to control a couple of settings in the GT-8, I have it set now to globally toggle the OD and Tuner. The OD is set different for each patch, but I am primarily using the Booster, direct signal maxed out, effect level zeroed out, just a volume boost = solo button.
Hitting the CTRL button puts me in manual mode, meaning I have a bunch of stomp boxes now instead of presets. This is really handy and allows me to use only three patches so far. I have two clean, one of which is wet, each of the two has a different delay/chorus/EQ/Comp/Wah settings. Each patch has two more effects available via FX1 and FX2 in manual mode, each effect can be unique. I have a badass univibe solo sound I've been digging...it reminds me of Jimi
Right now, i have a modern rock crunch going on in one patch and a pseudo metal patch that I don't like much (it's using a preamp model...the cleanest I could find and still has that wet blanket over it).
The effects are very useable, and have the option for delay spillover that I love. I can see this being my ZZ Top rig.
Funny story about the ZZ band; I brought the GT-8 to practice & ended up unplugging it. I used the amps channel switch instead. It has an EQ toggle too, which is a great solo boost. I used that pedal and the guitar plugged straight into the amp for the whole set.