Im dropping into this thread a lil late, but I would prefer having a mix of both. Muscle backs for 9-6 and cavities for 5,4,and 3. The new titleist zb forged have this great setup, but I hit a demo 6 iron and it didnt really feel all that much different than the 695cb's I currently play. The muscles seem like they allow the player to control the ball more with the realse of the club more than cb's do. Maybe its just my imagination.
I havent found any differnce in forgivness between a blade and a game improvement iron - really. You need to put a good swing on either style to have a good result. Irons with big offsets have always confused me in terms of set up, so i have always gravitated towards blades because of the simple lines. I learned the game with blades and I feel im the better for it. It allows me to focus more on the ball rather than this big spaceship sized club sitting behind it. Plus, the gratification of hitting a good shot with a blade is much better because you know it was you that hit that shot, and not the technology of the club you are using. I think as far as cb's vs mb's go, its about personal feel.