Nanoraptor and Ignitor 29er
I have both mounted on front rims (I run road rims 19-20mm outside width). The Nano is about 1/4" larger diameter, casing for Nano is 52mm wide, for Ignitor about 51.5mm. I did a roll down test on the two a couple of days ago on the street in front of my house. Over two blocks there was 5-10' or so more roll out of the Nano. I didn't measure top speed, used the same rear tire for both, so the effect may be greater for two tires. I have ridden both several times on the same hard packed granite sand roads and single track with a little loose gravel or pine needles. I havn't been able to detect a significant difference so far, but the weather changes between rides and the trails are drier or wetter every time out. The Ignitor may have a little better traction cornering hard, but then just knowing it has better side knobs may make me feel like it is better.
Both are obviously cushier than the Continental Vapor and Schwalbe Little Albert as they are quite a bit smaller. I just got an Exiwolf and hope to try it this weekend. I also want to put a 26" Python up against the Nano and Ignitor in the roll down test just for fun. I'll see if I can get a post up about that.