These kinds of questions are usually reserved for Trackhead. He seems to be the minimalist guru around here. It's taken me a year to go from Asics 2070s with huge rigid orthotics to nothing but H streets and barefoot running. You just need to do it gradually. I've done 3+ hour runs in the H streets now, but I mostly shy away from any sort of pavement.
I used several transitional shoes along the way. I started by just not wearing my orthotics every now and then. When that seemed fine, I started working in some lightweight trainers (I think I was using the Nike Air Talarias...remember those!). Then I started doing some runs in the Nike Triax TC. Then I worked down to the Asics DS-Racers, and then spent most of last summer in the NB RC240s (with a lot of the heel cut off) and Asics 15-50 spikeless cross-country shoes.
By time XC rolled around last year I was up to hour runs barefoot and had done some 20+ milers in the Puma H streets. This winter I experimented with using aqua socks in place of barefoot running when there was snow on the ground.
Now, I train pretty much exclusively in the H street and barefoot. Hope that helped. You just HAVE to listen to your body. Wow, it's so ironic that I'M saying that...people have been ragging on me for that for the past 8 years.
Oh yeah, and I certainly DON'T do 150mpw all at 6min pace. Most of it is at 7min pace.