I interviewed Frank Robinson a year ago for a couple of UK magazines. The headline on the subsequent articles was "End of the line for the R22?"
Frank said he was considering stopping production of the R22 for several reasons. The model had been overdeveloped - it started out as 108 hp and now it's 180 hp with the same drive train, it's been blown out to 1370 lbs and you can't do any more with it. He'd already stopped making the Mariner and the instrument trainer, and his company's primary focus was on the R44, for which he was fighting off customers.
Furthermore, he believed the R44 Raven II would make the best trainer ever. Two up, it has massive reserves of power, it handles benignly and, he said, it would make the safest trainer ever built. It would be cheaper than a piston Enstrom, and cheaper than a Schweizer 269 with similar equipment.
Add to this the fact that the margins are greater on the larger machine, and that even with his new factory extension he's fighting hard to get the waiting list for the 44 down, while planning relatively big margin developments, and you can see his point.