Anyways as always test these mixers with smaller transactions, never send any coins anywhere if you can't afford to lose them, and keep your eyes open. I guess after all the years that bitcointalk may still be king for a reliable source to aggregate this type of research.
Do not know, but you have to stick with some famous mixers because the use depends on trust, even with small transactions everything can happen, such projects can be turned into scam once they get enough level ---->
BITMIXCOIN.IO scam confirmed: 16+ Bitcoin stolen.
For example, some mixers have paid a lot for signing campaigns, so they will not risk wasting their reputation for scam.