Well this has been really interesting, thanks for everyone taking the time to do this.

I have been VERY surprised with the results. Putting the Audya aside, I expected to like the Korg best, but it wasn't that simple:

Roland.
The BK7 was the biggest surprise for me. The drum kits are indeed excellent (except the brushes which are the worst of the bunch), the big problem is with the patterns themselves, often they are unnatural and lumpy, sometimes the percussion instruments used are totally random and would not be played that way in real life. If Roland were to use real drummers to play the drum parts of the Midi style (using a Midi Drum kit) it would make a huge difference. The BK5 didn't sound quite as good as the BK7, perhaps this was the recording, not sure. Diki's recordings were very good quality, and at 320kbps there is almost no audible compression.

Korg PA3X
The Korg patterns are better than the Roland ...although many are obviously programmed much slower as the tom runs are just silly in places! Many are still too jerky though and actually sound like something I might do if I were programming a style (I am not very good and my styles sound too mechanical..like a walking Robot)! The percussion instrument samples are good, but not quite as good as Roland's BK7, but the brushes are far superior to the Roland and are the best Midi brushes I have heard. The Crashes...they are all over the place, lots of different pitches and all over the stereo image which is odd sounding

Yamaha
The Midi Drum instruments are the least impressive of the bunch (Maybe the Tyros is better?) and the drum patterns are quite messy. Again....why are Yamaha not using drummers to play the drum parts instead of keyboard players? The Audio drums sound much better than the Midi drums, but the patterns are not great and I am not convinced these are 100% real drummers - sounds like an Audio recording of a Midi Drum style mixed in with some real Audio which is a little weird.

Obviously we all have different benchmarks, and I am glad we have the choice of all these different instruments. Although I couldn't go back to midi styles, I would not want any of these manufacturers to stop... or worse disappear. Its bad enough that Gem and Technics have gone it would be a disaster if we lost another.

Is anyone here a drummer, I would be interested to know what they think?