Well, I can tell you who I don’t recommend! I had a poor experience with Hastilow USA when they came to a barn in Maryland in late 2017. The fitter did not bring any curb bits at all even though I told the organizer in advance that was what I was interested in. The organizer specifically requested that info from participants, presumably so the fitter could bring the correct assortment of bits. The fitter was running very late (IIRC, 30-45 min) so I had to wait around for quite a while. She then spent all of 5-10 min looking at the horse’s mouth and filling out some paperwork.
Afterwards when I asked for a refund because I hadn’t gotten the advertised 30-min time slot or the ability to try any bits (which was the whole point of the clinic, I thought), I was told they didn’t write the ad and never promised a specific amount of time or that you could even try bits.
In the end they charged me both for the clinic as well as the trials of the bits they mailed me (which, by the way, were the exact ones I wanted to try just from reading the Neue Schule website so I don’t think I even got the benefit of an expert opinion). I might as well have skipped the clinic, which was 1.5 hours away and required me to take an afternoon off work, and just ordered the bits to try myself. I went back and forth with Hastilow for a while and got nowhere, so I had to do a credit card dispute to get my money back. I absolutely would not recommend them. Too bad because I thought it was an interesting concept and it sounds like other people have had great experiences!