90 is a big step up from a 50 and I dont consider the cost versus performance worth it personally. I had 2 90s and got rid of both of them. Fuel consumption is double, and most parts cost twice as much. I also find people with 90's dont progress well unless they have a 50 they care a lot less about to thrash around and try new stuff.

Don't get me wrong they are great machines, but they cost a lot, usually need more specialized tools and building skill and don't fly all that much better than the 50s.