Honestly, I have very little experience actually using fixed blades, despite owning a few. For me, the CRK OPK's are appealing for a lot of the same reasons that their folders are; well engineered, streamlined designs, beautifully executed. It also doesn't hurt their appeal that they are discontinued. As far as actual use, I don't have much practical experience or knowledge of their durability, but the hollow grind of my Shadow I out-bites all my other large fixed blades (Junglas, TGLB, Trail Master, Recon Scout) in chopping.
Whether the thin hollow grind in A2 is as durable, I don't know. That's why I've been so interested in hearing from anyone who has bought and used an Impofu, it looks to have a similar hollow grind, but obviously in 3V.
The one thing to note is that the round handle does require that more attention be paid to the blade orientation. It helps to choke up a bit to use the guard as an indexer, but that doesn't help much when you are swinging from the butt of the grip. Of course, this is mostly a problem when trying to chop with one of the larger OPK's. I'd imagine that it's much less of an issue with the smaller OPK's.