My personal 18V cordless is a DeWalt. The batteries seem to retain their charge quite well, when it gets left alone and unused.
I've never had to recharge in the middle of drilling anyone's exhaust manifold.
My maintenance department at the 3M factory where I work, has a Milwaukee 14V that has seen more heavy, hard, nasty use in the 4 years we've had it, than a 5-dollar ho in 6 years at the Mustang Ranch. (Can't vouch for that comparision, personally

)and it's still going strong! I used it over the weekend, and it drilled 4 3/8 " holes in 3/8" steel plate, plus 2 more in 1/4" plate, without running down.
Oh yeah, about the hammer drills. I own both a Bosch Bulldog Rotary Hammer with the SDS shank system, and a Hilti TE-55 Rotary Hammer with the SDS-plus shank system. Both are great, but the Hilti is made to go the distance. It's for sale, BTW, if anyone wants it, drop me a line. I'll email price & pics. Brand new, used once.