I've always wondered about that.  I can see where they'd be worth it if you used your tool many times a week to to the point of draining them, but cordless drills around here don't get used that often.  I've got a cordless Craftsman that's over 10 yrs old with NiCad batteries that still work fine.  Things like laptops, cellphones, pocketpcs, and cameras have been teaching me that lithiums are junk after 1-3 years. 

  Are lithium cordless tool batteries good like that for the long casual haul, or just short term heavy use?  I'd hate to pop the big bucks for lithiums and have them die after 1/3 or less the age life of NiCads.