I did find an M93 just before the UBR "beta" started up. Problem was the owner was asking $250 for it and I wasn't about to pay that for a used stock that has been discontinued.
The UBR has the same functionality, though it seems a tad bulkier. The UBR is also somewhat simpler to set up and operate. However, if I ran across an M93 for, say, around $100 to $150 and it was LNIB, I'd probably pick it up.