Running 42 Conti Crossrides now.
Did 30 mi of fire road last weekend and 96 mi of pavement the weekend before as well as the daily commute.
No difference to speak of in rolling resistance, or time on the 96mi route over 24mm slicks (@90 psi) when inflated to road pressure, (65-70 lb)
What I have noticed is increased sensitivity to crosswind gusts. Seems like they knock me around quite a bit more than on the skinny tires.