Yes, there is a huge difference between 240Hz and 360Hz. As I said, 390Hz came out only 2 weeks ago, so I haven't seen that model myself, yet.

Upgrading from 60Hz to 144Hz only makes sense if the money is tight. Because, generally speaking, with higher refreshrate you get better response time \ input latency.

Also, a lot of pro teams are sponsored by zowie\benq, and they still don't make any 240Hz+ monitors yet, but pros are contractually obligated to use it. On another hand, even if some of them aren't sponsored by zowie, they still get it, because just like you they see that everyone in the scene useses them.. They're copycats. Lots of CS pros are unfortunately completely clueless about peripherals

Basically, if you truly can get anything, I think there is no reason to get 240Hz over 390Hz, it's actually insane that it doesn't cost a lot more