In my opinion, one of the issues with RoR is resources. RoR/Mongrel seems to take up more than LAMP. Not too sure why, but I did see the results of it while working at my last regular jog (freelancer now). They had a program built in RoR by some Russians that seemed really buggy, slow, etc. Maybe it was the programmers, maybe not. Although, if you're going to run RoR, I would suggest running a Mongrel cloud and routing through Apache. I did some research on that (part of a proposal to speed up the companies online web applications) and most resources stated 5-10% performance boost. The other issue is definitely lack of documentation/references. Without that, who wants to take the time to learn a new language/framework when you already know one that works?