I think if you basically feel good about your regular T, that you trust him and like him and feel that you have a good connection, then you should stick with him. Part of what's healing in T is the relationship and juggling different issues with different T's strikes me as a bad idea. It particularly seems like it might be a suboptimal strategy for borderline issues because of the tendency toward idealizing or demonizing people based on how you feel about them at the moment. (How will it be when you're angry with one T and feeling warmly toward the other?) I notice you don't say that you strongly prefer a female T, it just sounds like you're wondering if you should choose one for this. I agree with RTS that it comes down to fit and personality.