I have a Kubota B7500HST with R4's and a Ford 1210 hydro with R1's. These are similar weight tractors according to the manufacturer's specs, although Kubota allegedly weighs the tractor dry and without tires. The R1's didn't seem to hold up real well on blactop, so due to that and the fact the Kubota has a FEL, I went R4 on it. I previously owned a Cub 154 Lowboy (2WD) with turfs, and without chains, you didn't go at all in the snow. Wet grass could be a challenge sometimes.
The R1's don't seem to fill with mud as much as the R4's.
Neither type chew up the grass unless the ground is wet, or you make a tight turn (particularly in 4WD)
The Ford handles a 5' rear blade in the snow about the same way the Kubota does a 6 footer.
There are places I need to tap the Ford into 4WD or raise the RFM to back up some hills. Neither is necessary with the Kubota. I don't notice much of a difference on sidehills.
Right now I'm replacing the R1's on the Ford with another set of R1's. I wouldn't be afraid to go with R4's instead, but it would require replacing the wheels as well.
I've had the Ford for around 9 years and the Kubota for about 1-1/2 years (220 hours and counting on the 'Bota, many more on the Ford). With the snow, dirt, etc. around here, I can't say there's a big difference in performance between the two types......................chim