I don't really think bb height matters that much when manualing, you just have to get used to the differences, and change your technique accordingly. I've had several bikes, +20 control, +35 dob, +45 GU , a saracen mod, and an echo team mod. I can manual them all quite well, except for the DOB, it seemed to flex and twist too much when I was on it... I find with longer frames, to get started you have to use a short pedal stroke, makes it a lot easier. Likewise, learn to pull your arms in when the front comes too low, it's an odd technique, but BMXers use it often.