I use Spendor S100s which are an earlier incarnation - I don't think the differences were huge between the S100 and the SP100 - I don't know what changes they made to make it the R version though.
They are big, but a lot of that is depth, they don't dominate. They will also go closer to the wall than you might think and don't overly excite any of my room modes. In room a frequency sweep tells me that despite the specs saying the bottom end is -3db at 45Hz, there is plenty of useful output down to 30Hz.
