I've owned a Vetta II, POD and XTLive. I want amp modelers to work SOOOOO bad that I keep buying and hoping and the results are always the same. By themselves they don't sound bad. Straight into the power section of an amp they don't sound bad. Direct into a PA they don't sound bad. Stacked up against other live musicians they don't sound bad.....because you can't hear them!! They don't cut. There is no definition, no spread or bloom and the tone is 'sterile'. The only way I got them to work was to take the bully approach and muscle my way into the mix through sheer volume.
I played in a Floyd tribute band with the Vetta. The other guitar player used a 4x10 Bassman and the Vetta was so very weak and thin in comparison. It was also extrememly directional. If you weren't directly in front of the amp you heard nothing. I spent months tweaking, and tweaking and tweaking and nothing I tried helped that amp cut. I ended up buying a Traynor 4x10 80 watt tube amp and a few pedals and kept that in the rehearsal studio. (I bought the Road King for home use and gigs) The difference was instantly noticed, our overall sound improved ten fold and the jokes were endless!
I later grabbed the XT and whenever I tried using it, other than effects, in a band environment it was the same scene all over again.
I want modelers to work for me but until the day comes when I no longer care or desire to play live with other people and am just noodling in my home, I will not buy another amp modeler.