If the 210/4 would fit my needs, I would get it in a heartbeat. I have learned from experience, however, that I need f/2.8 for a lot of my work. Between shallower DOF and higher shutter speeds in low light (ever shoot cycling photography at dusk with a medium format camera?), the f/2.8 is what I need.
Well, can it be worse than the 210? It is supposed to be better glass with APO correction and the 2.8 opening. Other than the price it should be a much better lens and as you said the only thing that will do the job for you.