...maintain a gravel driveway...haul wood in the winter. R4s...still offer the traction needed for winter work.
I personally run turfs, but have noted discussion such as these in the past.
On finished turf, I believe R1's to be just fine if you can live with the chance of "chevrons" if you're on soft lawn. Turfs are perfect, but if they slip, they'll leave a mark. R1's probably won't slip, but if they do they'll leave a
hole.
You've worked with R1s, so you'd know better than anyone what they'll do to your gravel drive.
Some may have a strong differing opinion, but I believe TURF tires to be best suited for smaller snow storms. R1s have a clear benefit if you're buried and clawing through tough snow, but once the snow is CLEARED, I'll drive laps around an R1 equipped tractor.
This will really stir the nest, but this is my opinion about R4s: I'm starting to believe that they aren't the
best of both worlds, but the
worst of both worlds. They don't have the deep lugs of R1 tires, so they'll only do so well in the dirt. They don't have much bite in turf. Nor do they have many "shoulders" (as turfs do) to work in the snow. I think R4s look good and are well suited to forklifts to distribute load while having more bite than a "slick" tire. But tractors need either R1 or Turf, depending on the function.
I would think you'd be best off with R1s.