Chris, the original poster already has had success with 70 mpw. Why back off from what has worked? I can't think of a single example of a successful runner who has found more success by backing off of a moderate training regimen. I can think of many who continually progressed in performance level through continual progression of training volume and intensity (to think of one name that most of us in Wisconsin know well, Chris Solinsky).
I don't think anyone is suggesting that the original poster goes out and beats his head against the wall by dramatically increasing his training level. However, seeing as he has had success at one level and has matured another year, it's only logical to believe that he can step it up another notch to continue his progression as a runner. A regression in training is much less likely to result in a progression in performances.