I'm looking at AS ball heads, and wondering if it make sense to get a used B1 as opposed to a new or used Z1. I'm aware that the AS clamps are not the best, but I have found an older B1 that has no clamp, just a protruding stud waiting to have a clamp added. I like the panning knob on the B1 better than the Z1, and I don't need the extra weight capacity of the Z1. Further, I don't like the pan markings on the Z1, they aren't numbered, or engraved. So, can a user just easily add a RRS screw clamp to the B1 stud, or must it be done professionally? Do I give up anything significant in going with the B1 over the Z1? I might be able to get into a used B1 with a RRS screw clamp for around $300, so how does that sound? Anything particular to lookout for in a used B1?