With Line 6, you’re investing in a certain set of priorities and a specific track record, and with Fractal you’re investing in a different set and different track record. Their products reflect that, even as / if the Line 6 amp modeling catches up with Fractal’s own.
Both have great longterm support, with the only caveat being that Stadium will probably be supported for longer than current gen Fractal (even if current gen Fractal still has years of support left), so I don’t think you can lose there vs some other companies that are more unproven there.
I think that if someone is approaching the Stadium with the perspective of “why wouldn’t I just get the Fractal at that price?”, then they see the Fractal units as better, and the Stadium as a compromise, because Fractal’s set of priorities probably aligns more with their own, and then they should just go with that. And in that case, if anything the higher Stadium prices just makes that decision easier for them.
If I was going for a modeler to use as an all(or most)-in-one, I don’t know which way I’d go, but I’d maybe lean Stadium because of the fun factor, future capture capabilities, and because I don’t really enjoy making patches on the computer outside of some specific cases—and it seems to me that the amp modeling gaps have been closed enough for my tastes too. The Fractal stuff really appeals to other parts of me though, and I actually like the rack format quite a bit for my uses.
In reality though, if anything I’ll wait for the Stadium Stomp or an amp version of the VP4, so I’m not really the market lol