Get the stainless if:
A) You wear platform shoes (preferably white)
B) You wear LOTS of gold chains, rings, etc.
C) You have a polyester fetish
D) You enjoy 'posing' with your pistol in front of mirrors
or
E) You just really like it
Seriously, I think they're both just as durable. The HE finish gets a bit of a shiny patina on the edges after LOTS of wear, but it doesn't wear through. I think it looks good this way, but I'm weird like that. I've got more if I ever need that spankin' new look.
My brother, the pimp
, has the stainless slide, and it seems to hold up just as well, without the patina. He doesn't have a CCW, though, so it hasn't been carried...
Personally, I find the sun glare off the flat-topped, shiny stainless slide to be a pain in certain situations.