I agree with the infrequent firmware updates that's really starting to annoy me when I look over at Fractal Audio and see they're at version 10x or whatever for the Axe-FX II....as for the the Edit software yes it could be better, I don't know if I would trust it on stage setting but it works really really well with my dream rig, I love turning a knob on the DT, HD PRO, JTV, pressing down on the foot-switch of the FBV and seeing whatever I'm doing in real time on the edit software from any of the devices I mentioned...maybe that's due to the fact I'm using the POD HD PRO Edit software, I don't have any of those issues you mentioned....
I'm also a little concerned in the original YouTube video L6 posted yesterday about the 500x, L6 compared the POD HD 500 to the iPhone 4 with the HD500x being the iPhone 4s....that leads me to believe if I'm going to stick with Line 6 for my rack FX and amp modeling, I'll need to buy a new device every year just like I do with apple (although I get the iPhone's for free since I simply trade in the older iPhone....hmm something to think about Line 6 a trade in program right???)
I really like the way Fractal Audio handles the AxeFx II with all of the updates I've seen released....having said that, I don't have that kind of money for the unit in addition to the foot controller....but if I'm going to have buy a new L6 device every year to keep up...idk Fractal sounds very intriguing to my nerdy amp modeling mind....