I think the only fair comparisons are when you look at contemporaries.

The Owen was a very reliable piece of kit in general. Much of that is down to the magazine and the "over-thinking" in the internal design. It is quite heavy for what it is and that, more than the "compensator", probably helped a lot. The "assemble from the front" idea is interesting, though the constant dismounting of the barrel would have to result in wear of the seating surfaces eventually.

In my earlier days I managed to fire a couple of different marks of Owen, an Austen and the F-1. The F-1 seems to have been meant as a "bullet hose" as the sighting equipment was obviously an afterthought. They were, however, capable of some nice shooting. Once you got the feel of the two-stage trigger and could confidently fire single-shot, it was a neat tool for close quarter snap-shooting. The M-16 gives you a lot more wallop in the same role, however; ditto Mr. Steyrs "Tupperware Rifle". The Austen worked OK, but the magazines were a pig to load, unless you had the nifty tool that was supposed to be part of the kit. Quite pleasant to shoot and the "Chicago Piano" dual grips made "off-the-hip" quite controllable. Interesting thing is the grip panels on an Austen are almost identical to those on the Germanicon MP-40. There is something about the internals, too....hmmm........ The die-cast alloy housing for the magazine and foregrip is a neat solution to an engineering challenge, though I have no idea how it would cope with electrolytic corrosion in a wet / salty environment.

Any chaps with field experience on these?

One of the most interesting books on the subject of Owen Guns is, "The Own Gun" (surprise) by Wayne Wardman.