I've had both types of training, but that was while working as an LEO. I've never heard any OCers discuss actual retention training, but I'm fairly certain most of the folks I've met at our "OC Dinners" are practicioners of hangfire/misfire/failure to fire drills. I've trained my 18 year old OCing daughter in retention and we do LOTS of dry firing/drawing practice at home. We also practice room clearing for both 1 and 2-person situations. We do misfire drills at the range.
She shoots a .45 cal Glock 21 SF and wears a SERPA. I showed her the articles and complaints about people having AD's with a SERPA and she told me "Dad, those people are just boneheads... Watch this!" She cleared her weapon in a safe direction and inspected the chamber/bore. She holstered an EMPTY weapon and proceeded to draw it very quickly. It was evident to me she even practices a little when I'm not around. She's FAST and her trigger finger ALWAYS indexes along the SLIDE, and NEVER comes near the trigger or trigger guard.
More people really should practice these drills and talk about it with others. How you react in training is (hopefully) how you will react in a situation. I'm saddened to hear that SERPAS are no longer authorized for match shooting, just because a few boneheads screwed it up for the rest of us.