I would say stick with the same size front and rear for streety riding, having a narrower front tyre makes the bike feel weird when carving corners and stuff.
The Holy Rollers are very good, good grip, good feel etc, can't go wrong really, HOWEVER, the best tyres I have tried are the Odyssey Mike Aitken P-Lyte tyres My link
They are a bit narrower than the Holy Rollers, but nothing ridiculous and they are fairly heavy (over 900g I think) but the "feel" is the best I have ever felt, it's like they have lots of damping and stability, you can run them softer but they feel harder. It's hard to explain. With normal tyres running at 40psi, they feel like they will rim out and have a lot of vibrations though them which reduces grip and makes them feel like they will wash out. The P-Lytes don't have re-enforced sidewalls as such, but they don't feel like they will pinch as easily, at 40 psi they feel more like 50-60 with the "thumb" test but once on the bike they feel like all the vibrations are damped and it feels totally confident in the corners and more forgiving on the body.
shame they don't do a 26" version.