I've never hit with the PSL as the tight string pattern scared me off a bit. I know that the PST is fairly low powered but it has more power than the PSL and the Pres Pro has a good bit more CONTROLLABLE power over the PST. It took me awhile to get it dialed in but I love it now. I've been using it for a month and am glad I switched but I did love my PST.
Poly really adds to the SW (not sure about the exact addition) but I love the control it gives me. I usually string 55/52 and it's a nice combo. I broke my alu power tonight so next I'm going to try out some KBaum PL2 and see how that goes.
You're so right about 17g strings in a tight 18X20 pattern. My son uses a prestige mid and started out with 16g kpro gut in there. He eventually move to 17g and I could not believe how much more feel the 17g had over the 16. Even visually it was much thinner and played much better.
At any point were you approached by a man in a poncho offering peyote?