I Run a Honda 476 hrx roller plus sides are light, fast, large simple clever grass bag, light very easy to turn, belt drive so smooth lots of control feather the speed if needed, powerful on thick grass large chute and great on large and small lawns.
Minuses Height adjustment terible very cheap thin lever and low range from like 15mm to 60mm. Some parts are very poorly made its been back to dealership under warranty 3 times for drive pins and clips breaking the dealers have been very good but on the most expensive 19 inch roller mower in the world I dont expect this sort of build quality or to be abandoning mowing jobs cause brand new mower with 20 hours on it does not drive. I also feel for such a cheaply made machine Honda charge way way to much for parts which will be a huge problem when out of warranty labour is no trouble as its very easy to work on its the cost of parts what will kill it in the end.
Over all I like it its a pleasure to use I think 19 inch all the way I have set the revs to around 3500 rpm it realy cuts quick and well like this. The factory set 2800 is like mowing on tick over. I think higher revs and better cut make it superior to 21 inch.
I have used pre 2005 Hayter 56 which I love to bits ( new one differnt mower awful )
but the deck breaks and cant be repaird easy. The 476 is simalar in cut quality and manouverbility. I have also used a Honda 536 roller which I think is just awful. The main reasons its so terrible are because its 60 kg the handle bars are miles long and roller is tiny therefore it has the manoverbility of an oil tanker. The gearbox lasts only a few tanks of fuel and is horrible to use it goes clunk bang its either off or on so rough click click click bang then drives then up a mild slope will disengauge allowing the handle bars to jab you in the guts. Also unlike my 476 which rams grass in the bag to the brim it would only 3/4 fill a bag I never got on with these Honda's I know some people love them each to there own.