he was using a scubapro mk25, beloved of tec divers everywhere
This does seem to be received wisdom, but I don't like them. I've had cold water freeflows with them too often, and I find them temperamental. My overall favourite is the Poseidon Jetstream (I don't like the X-stream at all) and various Apeks are very good as well. I also find the performance of several Aqualung regs remarkably good.
Most of what you say does seem to be good sense though.