Are knobbies really needed for XC Muni?

[RIGHT][/RIGHT]When riding on a hard-packed, well-worn, dry, mountain bike trail - nothing technical, just flowing cross country - do knobbies provide on advantage? Or are they a hindrance (similar to knobbies on pavement)? My theory is that a large volume road tire might be better for much of the trail (with the possible exception of too much tire slip on steeper uphills - not that I am all that great on steeper uphills).

Anyway, I have a Nimbus 29 (with road tire) that I really enjoy riding. I will try it in place of my 24" Onza - if only I can find the time to actually do it. Maybe next week. In the meantime, I am interested in hearing the wise council of this august group.

on the type of trail you describe, knobbies would have little advantage…i ride slick in the woods all the time, and the only times it seems to be a hinderence:

-wet grass
-steep hills where high back pressure is needed to maintain grip

I ride dirt on my Coker with a Radial TA tire, no problems. Don’t do it in the wet much though…

Knobbies are most useful for turns at speed, and keeping traction on the ups and downs. For light XC you should be fine with a (fat) road tire. If the tire’s real skinny it might not be as much fun.

Sticky rubber helps as well, most road tires are not sticky which is how they last longer.

If it works, then do it.

Where I live, in the Southeast, rarely is the trail so dry that a slick would be usable.