I've seen/built/repaired more dies that were back mounted than face mounted. This is only my limited experience but it was with several stamping houses. Smaller issues like cam adjustment, form galling, and some forming operations can/are face mounted for removal/adjustment while in the press if the die was well designed. But for major problems (like chipping/fracturing of the CE, doubling, slug-up, etc.) a repair while in the press it may not be a good idea to tie up the press while a time consuming repair is effected. Sometimes it's better to just yank the die set and pop a different job in or get the back up set off the shelf if it's a long runner. Some places I've worked had two die sets for the same job for obvious reasons. Some places also insisted on back mounting to eliminate the possibility of a SHCS vibrating loose and dropping into the operation. The potential for catastrophic die failure wasn't worth the "convenience" factor. Design precautions were always taken with face mounted components, particularly in the upper shoe. As for perforators, that's a matter of preference. Some like/prefer the ball-lock perfs and some don't. They have proved to be convenient for me sometimes but I've also had difficulty removing them too. The closer the fit the more difficult they can be to remove but that's just my opinion. I've never seen a face mounted die with transfer pins/plates or spring strippers that were face mounted, not sure I see a reason to either. I guess it's more about what you're familiar with. Repair has a point to the convenience of face mounting. Building the die I'd prefer a back mount. If it's a high speed press like a Bruderer then I wouldn't want to risk a face mounted ANYTHING as you'll never stop it in time to avoid damaging the entire die and/or press. This is all just my opinion and should not be considered anything more than just an opinion.