I don't have a problem riding and racing a 15.5" 29er, my inseam is about 28.5". I don't think unless you just often ride a course with a lot of hairpin turns you will have an issue with toe overlap. My 29er seems to corner better than my 5" travel 26er did, that bike always felt twitchy. I honestly have never heard anyone say anything about toe overlap in mountain biking, I don't know I guess it is an issue.

I know several women the similar build as me that went 29er and won't go back. But some people never want to give up their 26er.