Basically the delivery system is the ether-carbonate attached to the prosteroid. This prolongs the half life of the active ingredient so you have high blood levels throughout the day, hence it is more active. As far as i am aware no other supplemnt uses this -EC bond making the Biotest stuff somewhat unique. The Pro-steroid i think is more marketing than anything, basicaly because 1AE and 4ADEC are steroids. The term Pro indicates that it may convert to an other substrate (steroid) and then pose as an anabolic. In short i think Mag-10 is a solid product and you should give it a go if ya wanna bulk up!
As for putting on size with the T-dawg diet, yes ofcourse you could put on size if you changed the macronutrient amounts, total calories etc, but then it wouldnt really be the t-dawg diet it would just be, well, eating. The idea of bulking up on less than 100g of carbs is silly to me. Just my thoughts. I would stick with massive eating, but whatever you do, you gotta get you carbs if you are bulikng on MAG-10