Re: Those of you w/ the Eleven Rack....
POD/Elevenrack/Fractal stuff definitely shines in a controlled environment. With enough tweaking you WILL get anything you want out of them as long as you cut out as many variables as possible when recording. If you want to play out loud from modeler > preamp/transparent head > cab, you can do the same as long as you have a decent room. Can replace a lot of your pedals (not all, I still prefer my Dimebag Wah, for instance), and you can get a lot of unique sounds with some of the wackier settings and stomp models, bolster your creativity a bit.
I will say in the end though, and especially when gigging, it's much easier to get the sound you want out of the tools that made it. If you're looking to save money in the studio/in practice, any modeler of decent make and quality (be it Line 6, AVID, Fractal, or even your laptop hooked up to one of those software modelers), get whatever option is cheapest. Obviously youtube isn't the end-all be-all for comparison shoot outs, but the few that post in HD really illustrate how similar and how close your tones will be with the right tweaking and post production.
In short, I'd say any modeler is good, if you're asking about quality you're always going to find people on both ends of the spectrum who love/hate it. Get whatever fits your budget, and don't expect to just turn it on and be amazed. Lots of tweaking, can't emphasize that enough.