Extremely good post, boogie.
The one thing I will say about TP flying is that it hones your "hand flying" skills and airmanship. Whether you're barrelling about doing surveys at 8000ft, flight calibration at a couple of hundred feet, or flying pax around Scotland at FL230, you're never out of the weather. The high(er) proportion of flying outside controlled airspace increases your awareness about what else is in the sky, and the larger number of sectors that you'll do, hand flown down to Cat I minimums into sometimes fairly challenging strips is good experience.
But as an alternative point of view, if in a Jet the computer flies the aeroplane and the pilots are there only to program the computer, then maybe all that experience is irrelevant...