I have not read all the posts here yet, but I wanted to reply because I just (Oct 2016) bought a Gen1-Standard.
After day #2 (day#1 was only an hour or so), I can say it is great, and when I have the power speaker/monitor, it would be worth selling an amp or 2 and going with this. Maybe one day I will get the II or the AX8, but I can say the amount of sound I found on day 1, and how well they sounded, amazed me. I have not come close to dialing this thing in, I have made 2 patches of my own, and I have much to learn.
The biggest thing I have found is that it works best with an XLR cable and a power PA type speaker. The 2 way system with a speaker and tweeter makes it sound more like a modeling system and less like a pedal, if that even makes sense. When I plugged it into the front of my amp and used it like that, I was underwhelmed. Then, I went to the store and tried a powered speaker, and it sounded like a different system.
The guy at the store said to use the FX return plug to bypass the amp's preamp and it will sound better. However, at the end of the day, if you plug one of these into your amp, it seems you are limited to soundling like your old amp. I do not think there is some miracle device that will plug into any amp and make it sound totally like another amp and speaker. this is why the flat-response stuff is needed to get the most out of an AXE-FX. I am going to try a keyboard amp I have tomorrow and see how that sounds. I think the only hope for using a 4x12 cab is to buy a solid-state power amp, like the MonoPrice unit of a Crate Powerblock, or similar. I have heard some people use a Line6 Firehawk 1500, where you get both a guitar amp and a modeler like 2-in-1, I have to check that out more. Also saw someone used the Line6 AmpliFI, those are also modelers with 3 way speakers. Would love to find a way to use my Technics 3 ways I never sold that also have 15" woofers, tweeters, and horns in them, maybe I can use those with a power amp?
Anyway, I will read the rest of the posts, but I think the original Gen1 stuff still can be used, I have firmware 11 (Oct 2016). I did have to clean the VALUE pot, which is the main one, but that was not too hard to do. Best thing is, the Gen1's are around $600, and many more people can swallow that pill than $1500.
David