You'll love a 5er. I've had three. The extra basement storage really helps make up for the loss of bed space.
I run with a Reese 16k Titan slider in my Silverado short box and love it. Haven't ever really needed to slide it either. The Titan handles chucking better than my old Reese quik slide. There are rubber inserts that help absorb the chucking very nicely. I also have air bags and theyre a nice bonus. The new 5er has the mor-ryde pin box.... What a difference it makes too.
Titan and MorRyde...that's my choice.