dazco,
I have never used the slime innertubes, but I think that a lot of people don't think that slime is very effective against certain types of punctures, especially on the road. Some also complain that the slime can mess around with the valve on the tube, especially prestas. Try a search on this site. Theres a ton of stuff about Slime and other tire sealants that some think work better.
-Moab