I have a 700 so might not be of much help but... when I had OG Bighorns I went with 26". I've never read where someone needed to shim or change springs or anything like that after getting Bighorns a size up.
I wouldn't think you'd have any loss of low end at all with your set-up.
I wouldn't think you'd have any loss of low end at all with your set-up.