I've been using an R in my driver so far this year. I had one round where I loved it, but it's been a struggle since. I think it may just be the overall weight though as the shaft is much lighter than I normally use. I may try to find a heavier R shaft for it.
Also have an R in the used 7 wood I snagged and it seems fine. Honestly I can't always tell between R and S shafts. When I got fitted for my irons the DG 105 R300 and S300 felt identical to me so I went with R300.