Due Diligence on boutique European brokerages for prop desk setup

Hey everyone,

Currently doing some DD (due diligence) for a small prop trading setup. We are trying to diversify our counterparty risk and looking for alternatives to the usual prime brokers and retail giants like IBKR or Saxo, mostly hunting for customized execution and better margin conditions.

A colleague threw the name RMK Capital AG into the mix. It sounds like a Swiss-based boutique, but their regulatory footprint seems a bit opaque to me. I’m always highly skeptical of offshore or poorly regulated entities pretending to be institutional-grade.

I was digging around the web to find some solid background and stumbled across a pretty in-depth breakdown of their trading conditions and regulatory status, which raised a few red flags for me regarding their liquidity providers and actual jurisdiction.

Before I completely cross them off the list, I wanted to ask if anyone here has actual hands-on experience with their institutional desk? Are they just another sophisticated retail bucket shop (B-book model), or do they actually provide direct market access?

Would appreciate any insights or recommendations for other reliable boutique EU brokers.