Rock strewn, dips and holes and lightly snow covered I have navigated with my R4's unloaded but with 3900 lbs. The biggest issue I had was the log getting caught on some rock or making a turn and crabbing against another tree the R4's w/o chains would slip but I think R1 would too,
I dont have chains and probably will not get any because I dont run in the winter much anymore - just the fall.
You know what R1's do, and as RD Mcgregor said get R1's with a stiffer ply 6-8 ply.
You have to weigh it out - how much time is in the snow covered, then deep snow and if less than 10% of the time then R4's are fine.
Also, your JD chains - will they fit the Mahindra w/R1 or R4? You are going from a 20HP 750 to a 30HP 3016 if I recall correctly - i didnt check the tire sizes but thats one more thing to consider.