Tight spokes and proper suspension tuning will go a long way to protect rims, even the stock one. With that said, replacing the hoop with a stronger one, and then making it narrower than stock, will add even more to preventing dents (or worse).
And this coming from a guy that has a supersized/superlaced front hoop now.
'05.5 950 Adventure S "Bad Mutha F@&ker"
'04 R1150RTP "cop motor, cop suspension.."
'00 XR650R Dual Sport "Lil' Mule"
Conti TKC80 tire swing
"I don't know what you do, but I know what I do, and I don't do that." --Uncle Doug, R.I.P.
"Without the possibility of death, adventure is not possible"--Reinhold Messner