Personally I think the stretching part of the Doggcrapp training is very beneficial (as long as its done right) but painful as hell. Its one of the things i have incorporated into most of my lifts, but to be honest I have always been pretty flexible (years of martial arts training) so it may seem safer to me since Ive been doing it for so long. Of couse, you can take it too far...for instance, my left shoulder is acting up a bit so naturally Im gonna go easy on the stretching in that area until it feels better....then Ill ease back into it.
The thing about stretching hard after a lift is that it the PERFECT time to do it...youre warmed up, your body is already experiencing the stretch reflex, that is the absolutely perfect time to do it. IMHO you get more benefit from a few minutes of hard stretching after a lift than from a 30 minute stretching regimen starting from a cold or semi-cold status.
As far as which is better for size...sorry, but thats just a dumb thing to say. Are higher reps/high volume better for size, or low reps/low volume or low reps/high volume or high reps/ low volume? None AND all of the above are best...its all about learning what works for you, and continually pushing yourself to lift more and lift smart that will put good quality size on.
