In defense of Red Sail, I had the same impression about them being big and impersonal until we dove with them. We had a great experience on every dive. They are very safe and work hard to please.
I love Ocean Frontiers and will dive with them again, but have a big problem with the fact that they don't keep someone on board at all times. I actually had a situation happen, where due to unclear communications, our group got separated and I ended up as part of a rescue of a panicked diver....it's a long story, but it was my first dive after receiving my certification. If someone had been on board a lot of the problems would have been avoided.