Dunno, don't work for fractal or line 6 so no idea how related the code in the boxes today relates to the 500 to old axe fx standard, don't think of things that way. They can say it's all brand new but who really knows, we know all the effects aren't. I work in a software related industry and have seen many 'built new from the ground up' products that take a bit here and the from existing technology.
Price is relative to what you can afford I guess, the price difference you mention wouldn't come into it for me, wouldn't compromise on what I want for 10% or so difference, but I would say that a more or less 10% or so difference in price does to me put them in a similar price point (which is what I said, did not say same) - I'm lucky enough to have all three units right now, you mentioned you never tried a fractal, maybe if you could side by side you would hear, and especially feel a difference, which to me in pure quality of tone of amps and effects makes the helix less value for money. I don't need an audio interface, and don't really like the inbuilt pedal vs using an external one so for me, where the helix is in the marathon, I think I'm better off skipping to the half way point;-)
Anyway, at risk of this turning into one of those terrible vs threads, I going to back away slowly - will close with, as said before I like the helix, just not enough to to keep it. Hope it's does develop as a platform, if so maybe I'll pick one up again in the future.