Neither has much, just a number of Quantum Ursus NL's, a good knife if you like the style --I have one--and the first model in Shiro's new more basic Ursus line which feature SRBS and Cromax PM blade steel.
I'm with
Officer's Match
when it comes to SRBS vs MRBS as the action of the former is snappier and freer than the latter. However, of my two F95's, one in each bearing configuration, I don't find my MRBS to be more drop-shut than the other, nor is it choppier. It's actually a tad smoother. For me, the thing with MRBS is that it perhaps provides more lateral stability/strength than the single row configuration.
The action on all my BB Shiro's depends more on lube, maintenance, tuning, and simply wearing in--the more they're used, the freer they become--and not on the number of rows. I've got two Shiro's on washers too and the action on one--the Hati frame lock--evokes a CRK if it were a flipper. The other is a BMK-style sliding bar lock knife and not comparable. I'm not a big fan of roller bearings--I have them on my most expensive and prized Shiro, which is far from my best flipper--and agree with OM that they seem conceptually flawed. I think we've had that discussion somewhere over at
The Bears' Den.
Anyway, I've got nine CRKs and nine Shiros. They're all excellent knives, the two makers' output couldn't be much more different, and I appreciate both for what they are. I like both flat and hollow grinds, washers and BBs, flippers and thumb studs.
I've got one AB iMamba, a PJ flipper on bearings. I like it a lot, and it is quite reminiscent of CRK design language. It's kinda like the missing mid-sized Sebenza, though being a big knife kinda guy, my large CRKs (all but my Mnandi) seem sorta mid-sized to me. The iMamba's just a bit bigger than my Shiro NeOn, which is a good small-sized knife for me. I sold my only small Sebenza coz it was just, well, too small.
Lastly, when it comes to ball bearing systems, I have no problem with loose bearings. They're a bit more of a pain to deal with when maintaining, but it's no big deal to me--I just try to stay calm, go slowly, and be kinda Zen about it. Shiro BBs are free in open cages, which seems a good mid-way system for reduced friction between fully caged bearings and completely free in races like the iMamba's IKBS style, though I've wondered if two adjacent free bearings could bind against each other if touching and end up sliding instead of rolling. Perhaps a thought for another day....