Hi there. I'm currently on the same hunt as you are. My latest string job I tried the PHT main/VS crosses, and it's unreal. 18 hours so far and although the original pop and sick spin is not quite where it was from hours 1-8, it is still playing great in my opinion and I've put a number of string savers in to make it last and keep the stringbed as tight as possible. Last night I could definitely tell though that the PHT is starting to die, but until it plays horribly, I'll play them til then or when they break just due to the cost.
My next try is to use BDE natural gut instead of VS (it's about half the price), then considering how that goes, I might try a multi like NRG, but I'm having my doubts, because before I did PHT/VS, I had a hybrid ProSupexBA/Wilson Sensation (it was free- and total garbage multi IMO), which left a bad taste in my mouth for multi's vs. nat gut for the crosses. That said, I've heard that multis like NRG, X1, ProSupex MaximTouch, etc can be decent replacements for the gut, but even then with mixed reviews. I'll give one of them a try after BDE to compare.
I'll try to relate my experiences as I go if it helps. I use a KBT strung usually around 60#, and I'm a 4.5 baseliner with a decent all-court game. I rarely hit flat shots except for my 1st serve at times (just to give a point of reference and comparison, since we all will prefer different setups to match our style and likings).
Good luck! I'd like to hear how your experiments go as well!