The fact is that I checked how they work with Monero, this is the only mixer that can do it.
That's because there's no point in mixing Monero when used correctly.
See:
#2 - Monero
Monero is not a magic black box which provides perfect anonymity! If you use eg. flyp.me to buy XMR and then quickly sell this XMR on flyp.me again, it is blatantly obvious to flyp.me what you've done (if they keep logs), both due to the amounts and the specific Monero inputs used. In order to get decent privacy, you have to do something like this:
1. Convert BTC to XMR (using your own Monero wallet, not a hosted wallet).
2. In two or more transactions of random amounts, move XMR from that wallet to a different wallet/account.
3. Optionally, you can repeat the above step with additional wallets/accounts for greater anonymity.
4. Preferably in two or more transactions of random amounts, convert the XMR in your last wallet in the chain to BTC.
Ideally, all of the above should be performed over as long a period of time as you can tolerate.
- Pros: Possibly the best anonymity, especially if you're able to stay within the XMR ecosystem to some extent
- Cons: You should use Tor with Monero, but you have to set this up manually; it's all more difficult; you're exposed to exchange rate risk; transaction fees may be significant