well, I think you need to look at it from the perspective of the instructor. You are a new student coming in to check out what he is teaching. You are claiming some experience with other methods, but he doesn't know what your true skill level is. So you are a newbie and he probably feels he needs time to assess your ability and how well your skills may or may not mesh with his methodology. So he has you start as a beginner and he teaches you like you are a beginner so that he is certain that in his method, he is teaching you thoroughly and completely, and hasn't skipped over something based on a possibly false assumption that you already understand or know it.
I have no experience with Krav nor with san soo, so I cannot comment on how similar they may or may not be. It is my experience however, that often things that might look similar on the surface, can have some subtle differences underneath it, and those subtleties can make all the difference in the world. Those things take time and close attention to sort out.
So again, I suggest that if you decide to join another school, you embrace being a beginner in that school and do not assume nor expect to advance any faster than any other beginner, in that system. If merited, you may advance faster. But a lot of that depends on the instructor's judgement of what is the best way to approach your instruction. And of course none of this means anything with regard to your status or abilities with san soo. It doesn't take anything away from that.
Nicely put.
I've been with my current teacher almost a year now. I've practiced one of the martial arts he teaches (Choy Lay Fut) for quite a while but a different branch. I'm a beginner in his school, but granted I move much easier & comprehend far more than the other students there. Did my ego (which yes, that's the problem I'm seeing here) get in the way?? Hell no!! He has something good to bring to the table, I can clean off my plate to take part in it.
Best thing I can tell you from what I've read, check your ego & your black belt at the door. If you're going into somebody else's house, you play under there rules. Or don't. Your call, but don't expect special treatment from lots of places due to past experience. Most of the time it doesn't matter, it can just give you a head start in comprehension of the new material.