I emailed Xootr early on about a taller riser. They got right back to me, but said the taller risers are long gone.
I do use a Surly Tugnut on the rear. I haven't ridden the bike without it, but I've had issues on wheels sliding forward on previous bikes with track ends. Those bikes were mountain gears, so lower gears which puts more tension on the wheel. Maybe the Swift doesn't really need it, but it's not hurting anything until I need to remove the wheel. Then it's one more thing to juggle. I think a cheaper BMW tugnut would work just as well, but you might be able to fit a 1.75" all the way forward anyway. I only had the 1.95" tire to use (and the cheap 1.5" tire the bike came with). I also wanted to get the longer wheel base of the extended chainstays. I think it gives the bike a bit more stability.