Yeah except for the fact that professional road bikers have the lower extremity bone density of 80 year old women.
In terms of training for climbing, I believe running is superior for a few reasons:
1) The high loading in running makes it the best bone-building exercise possible. So especially if you are female, running now can help prevent osteoporosis. Also, the high eccentric impulses into the lower extremity causes more deep tissue breakdown, thus over time making the muscles and connective tissues denser and much stronger (if you don't overtrain).
2) There is a greater "transfer of training" effect. Running (especially on uneven and steep terrain) makes for a very similar set of movement patterns as in hiking. Because of this you are training the same balance patterns and exact muscles as in climbing (well, speaking of the hiking part that is).
I also find it interesting that the literature shows that barefoot runners have the lowest incidence of lower extremity injury.....
I think it is a combination of the two. I simply cannot do my 2-3 hour intervals or hill routines more than twice a week. My legs get absolutely destroyed. Biking kicks my ass and my legs feel great the next day.
So, for those who cannot give up running altogether just run a little bit less and start cycling.