You are missing the point. Yes, people get fingers on the trigger early, often unintentionally, so why would you want a SERPA, a piece of hardware which further encourages this bad software? Go back and re-read Dr. Glen Meyer's comments about a human design concept called "affordance" in reference to the SERPA.
You may think you are keeping your trigger finger straight but if you were to video your self you might be in for a surprise. This is not unique to the SERPA, I can't tell you how many LEOs I've videoed on the range who SWEAR they are not doing X until I show them video or slo-mo video of them doing X. Patrick Sweeney putting his finger on the trigger in the Guns and Ammo "SERPA's are safe" video while talking about "training" and "just keep your finger straight" is a perfect example.
As for "regurgitation" , I've been in LE over 20 years and teaching firearms for over 10, five of those full time. Here are the LEO ND's with injury on the range I have seen or had first party information on in that time:
FLETC range: Beretta 96D & Thumb break holster - cause - holstering with finger on trigger and failure to thumb check. Shot in the leg, officer survived.
FLETC range: SIG 229 DA/SA - SERPA - on the draw. This is one of five ND's with injury which have occurred on FLETC ranges involving the SERPA. All occurred on the draw. Three were basic trainees, two were experienced LEOs participating in in-service training or qualifications. Guns include SIG 229's and at least one HK P2000 LEM V2. All five officers shot in the legs, all five survived.
Public range leased for FED LE agency: Glock 22. Officer is attempting to disassemble his Glock for cleaning after qualifying and shoots self through the hand. Officer survived.
Local LE range: SIG 229R DAK - Local LEO assigned to Fed Taskforce re-holstered and drawstring "toggle" from his jacket got caught in the trigger guard and discharged the weapon. Cause - Failure to thumb check hammer while re-holstering. Shot in the leg, officer survived.
Fed LE range - FED LE agent - Glock .40 cal and SERPA - on the draw. Officer shot in the leg. This agency has since prohibited the use of any holster using the trigger finger to release retention. Officer survived.
Local Agency Range - local LEO -Glock 22 & SERPA - on the draw. Shot in the leg. Officer survived.
FED Agency Range - Remington 870 & 12 gauge slug. Officer had Remington 870 slung with a 12 gauge slug in the chamber and manual safety off. Trigger caught on gear and discharged round, passing through the instep area of the Officer's foot. Officer survived.
Public range - Local LEO and co-worker off duty experimenting with AIWB carry with Glock 19 in. A private bay. Co-worker is "NRA Instructor" but not agency instructor. Femoral artery hit. Co-worker had no IFAK or TCCC training. LEO died. Unclear if this occurred on the draw or re-holstering. Officer was DOA.
Local Agency Range - Glock 22 and SERPA holster. local LEO shot himself on the draw after having issues releasing retention. "Through and through" wound to the leg with FMJ training round. Officer is lucky, no bones or major blood vessels struck. Officer survived.
FED agency range -Glock 9mm and SERPA. ND on the draw. Shot through the leg, nicking femoral artery. Due to the remote area, FI's apply CAT TQ and transport officer to the hospital half hour away rather than wait for an ambulance. CAT TQ breaks en-route but 2nd CAT TQ is applied en-route. Officer survives.
That is 14 ND's with injury 9 of which involved SERPA holsters. 9 out of 12 if you exclude the long gun and Glock disassembly ND's since they did not involve holsters.
This does not include the SERPA ND with injury at the local IDPA match which which myself and several of the San Antonio area PF members shoot regularly.
These are just on the range in a controlled training environment. What happens under real stress ?
ND's aside, the SERPA is of poor quality. We have destroyed. several in training trying to dissuade our officers from using them. In February of this year, one of our officers was assaulted on a vehicle stop. The suspect also attempted to disarm our officer. Though our officer kept his gun in the holster until backup arrived, the officer's SERPA was broken off the belt mount.