Dusted off my 1978 Seminole PA-44-180 Information Manual....
The technique you were shown is neither a soft/rough field procedure, nor a max performance takeoff procedure. Without a p-chart for that technique you nor I have any idea if it is REALLY better than the book technique.
Remember that it doesn't really matter to a professional pilot if the aeroplane can clear the obstacle both engines operating. You should be planning to clear it if the worst situation presents itself.
So...
Normal (recommended) takeoff procedure is zero flap. Manual states that this results in best flight configuration should EFATO occur.
Best takeoff performance (shortest distance to clear 50') achieved with Flap 25. Rotation at 63kt and climb at 67kt to the 50' height.
Compare this to the flap zero rotation of 75kt and BROC 88kt for normal TO.
Consider also that the procedure for EFATO with speed below 75kt is to close throttles and land ahead.
Should EFATO occur with Flap 25 set there is no climb performance information in the manual for the flap 25 configuration. All climb info is for Flap 0.
Guess its not a transport category aeroplane then!
So what does it all mean?
If you are obstacle limited, first do your charts on a flap zero takeoff and see if you have enough runway. Don't drag the stick into your gut, that's not the technique in the manual.
If you need to use flap 25 to clear the 50' obstacle, where are you going to put it down if you lose a donk after takeoff and prior to 75kts? Have a plan, my 2c worth, pick out somewhere long, clear and smooth within 30 degrees of runway heading.
If you are trying to get airborne from a soft or rough field, don't do it if you are also obstacle limited. Your technique has you spending a LONG time in that no-mans-land of being airborne, possibly below the 57kt Vmca and nowhere near Vyse.
I have been told and had shown to me, lots of different 'techniques' that the other guy thought were quite clever or fun or impressive, but really were flawed as to -- why would you use them?
I think your mates demo might be one of them.