You are kind of right fp. Rotary combines were always known for beating the straw, making for crappy bales and loosing straw through the stubble. Over the last ten years though the rotary combines have been given a second chance due to prices in the UK being so bad. The straw some years isn't worth a bean so trying to save it for baling and the sale of it seems pointless. The other thing was the climate. Rotary combines arn't too good in grain with higher m/c where as straw walkers will plod on through. Now though again due to prices, we want to harvest the grain at it's absoloute best quality, to do this you need to go when the time is right and as fast as you can. On this point the rotary's do clear up well!!
I drove Gleaner's in America, not a brand I knew anything about till I got there but having been a pilot on these things I can confess they are unreal. No gimicks or fancey bit's like the Case IH and the Deere's but that's the beauties. We ran with a guy who had CAT Lexion 570's in a few towns along the route and we left him standing. In Corn (Maize) he finally cracked and sold the four of them, finishing the season with second hand Deere 9610's.