Something I notice is that people who play private server, are usually people who try to play osrs but got bored because its requires a lot of work and grinding. This means that they never get to these type of end game content, usually not many people know how to do it. Honestly I feel as raid you can complete as long as you know the mechanics, you can really do it with mystic/d'hide/iban blast/rcbow etc, just takes more knowledge of the mechanics.
As for the drop rate, I honestly think unique here are a lot rarer then osrs. Maybe its because not enough people doing it/ maybe its because I have bad R.N.G/ maybe its because I'm just flat out unlucky. Who knows.
I can truly sad that the raids eco is asssss, reason I say this is because it may take 1-3 weeks to sell a dex prayer scroll? I'm not sure if its just that not enough people know how to make money or money coming into the game is very slow.
I'm not saying everything should sell instant but I mean I go into a raid and we get unique and I got to wait 1-3 week before I can split that loot? Maybe I'm all out of the head but again just my opinion.