Like I stated in my post it happened while driving my [diesel] truck. It wasn't the tune that caused it to stall, it was a faulty PMD/FSD.
I still use the P/M system on my car and have no issues with it as of yet, but I can see why the H/B system is a good upgrade for the higher line pressures that are attainable.
The only problem with either of these systems is that you have no [real] brakes when the hydraulic assist is disabled for whatever reason or cause.
You may have more luck stopping you're 3,500 lb. car than I do with my 7,000+lb. truck when it fails. I was just relaying my experience with a H/B system and the effects when you lose the power steering pump. You lose both the steering and brakes together with a H/B system which could be a handful if you are trying to stop while in a turn or need to turn to avoid ramming the car in front you.
Atleast with the vacumn system you get one maybe two pumps on the pedal before they go hard as a rock.
As with any performance mods there are trade offs that should be considered and what is most important to you will decide which is best for your driving style or use.