I can't compare the two screen types, but I can say that my rooted sLCD Incredible is getting excellent battery life regardless. Blows the Eris out of the water even with the same 1300mah battery, and we're talking twice the cpu, bigger screen... well you all know the specs.
If you can find an AMOLED, I'd go for it just for the nicer blacks, but if you can't, don't shy from the sLCD. It's a great phone.