We have run a 500 series head on a R52, when we bought the machine in 1997 the first thing we did was to buy an air reel, now this helped greatly but still didn't feed as good as the Deere 922 head that we were running with an older model 9600. We traded last fall to a R62 with the same comments as you were told, greater feeding and the likes BUT it really isn't that much better, yes it is somewhat better but that is due to the larger feederhouse opening on the 62, anyway back to the air reel for the 820 head also. We also tried a new Deere rotary combine, i belive it was the smaller of the two 9650 and with the new full fingered 925 it fed perfectly WITHOUT an air reel. This has been our beef for years about the Gleaner 500 and now 800 series flex heads, i have said for years to our dealer that Agco should buy a Deere flex head and make one just like it. It may sound like i am picking the Agco heads apart but in order for these heads to feed half decently they have to have an air reel where as with the 900 series flex head an air reel isn't required as it feeds so much better. I have told our dealer to find out a price on an adaptor and putting a deere head on our 62, it may look kind of odd but then we would be completely happy with a great machine and a great head too.