Just got back from courts hitting 50 platform serves, then back to my normal pinpoint for maybe 15.
OP swings the same with either technique, but moves his body into the court on pinpoint, which gives more power and less consistency, as he said.
I think a problem here....OP almost pancakes his trophy, so his loop starting the forward swing is only partial, and not enough to give him full power. if he pointed his racket straight up at the sky every time, he'd get more easy power.
OP is a big strong guy, and should serve effectively with any technique. His combi flat/slice serve is what he seems to hit, on every serve.
Not wild about the rapid fire serve warmup timing, as he never concentrates to hit a real serve, either fast or safe.
Both techniques were fine, but I like a pinpoint where the backfoot steps behind the front, not in front and to the side.
OP's serve is plenty good for 4.0, and he's possibly getting too old for 4.5 like me.