R4s are a couple hundred more than R1.
R1 is designed for maximum traction
R4 is a compromise between extended wear, durability, carrying capacity, flotation & traction
I went with R4s & haven't regretted it since getting them loaded until the snow this week. Past 2 winters they fought snow fine, but the slushy nasty drifts this week were to much. Not sure if R1s would have been much better though. I like the fact they rear up my yard LESS (but still leave tracks on non-hard stuff or when turning.
As I said before I have $1k of regret for not getting the extra HP, but not the $2k it would have cost me then.
In low range full throttle with good traction I can spin the tires at half go pedal. More HP probably won't make a lot of difference digging, plowing, or traction limited stuff. It will come into play if you do a lot of taxing PTO related thing.
For loader or precision work, NOTHING beats a HST. It sounds like you have bigger machines for pulling though. Why get a hatchet (gear) when a scalpel (HST) when you are looking at more flexible precise work.