Well, I recently changed from what is basically a Ki Society dojo (in other words the instructor is no longer affiliated but understandably has similar teaching and testing styles) to an Iwama affiliated dojo. My rank tansfering wasn't an issue with my new instructor. But usually this is decided on a case to case basis. I wouldn't think rank would be an issue anywhere. In my humble opinion (because I'm not an instructor) a person should be judged on their abilities. Some schools, like my old one, start testing at 5th Que. Some, like my new one, start at 8th. I don't think someone who has been in Aikido for 3 months and has just received a 5th Que ranking should try to transfer that rank to a new school which starts testing at 8th. Any decent teacher should be able to judge your abilities and time in Aikido to decide what rank you should be in their school. As long as they are fair about judging your level and are not bias because they didn't teach you, there should be no issues. Good luck. I hope your transition goes as easy as mine did.