For a long version of my answer, see my article in the next Mind&Muscle.net magazine (#24) due out soon.
Short answer: if you are in for the long haul, injectibles are very cost effective and convenient, like 15 minutes a week. Transdermals have to be applied twice a day, so you're spending about 90 minutes a week. -- Designer Supplements will be coming out with a new transdermal formula that will make it even more cost effective to use transdermals than injectibles. It is a matter of money and time. The effects are entirely dependent on how much of the steroids/prohormones are made bioavailable.