I hadn't noticed it before, at least for the Kappa's. I like that he's offering to replace or upgrade and not rip the entire original out and replace it. I tried that route and while it did make my 8's easier to power something was lost. I guess the best word I could come up with is depth.
When I went back with original crossovers the magic was back.
So I think it's great he's doing this, like you mention he's got great feedback so he's doing something right and it opens some doors for Infinity owners.
I'll never attempt any crossover work myself again, I know it's fun but if you can't wrap your head around what's going on inside it gets quite frustrating, at least for me it does.
I don't know if I shared my Speaker building experience here, I think I had a great selection of drivers, built some really nice boxes all by hand modeled after the Wilson Sophia, then completely waffled when it came to the crossover's.
I think I'm going to keep an eye out for some Renaissance 90's being parted out for the crossovers and have them refreshed while he's offering this service. Not that I'm looking forward to anyone parting out 90's but if that option became available I'd take it.