HNN, great discussion here!
I, like most others, started flying with the aim of joining an airline and flying the "shiny jet" - but as I worked through the industry my mindset changed and I ended up running away and flying in the military for several years before reaching the point that 10 months per year overseas or on exercise needed to stop.
So, when I wanted my life back, I rejoined civil aviation and identified that if I was to make a go of it, have enough financial strength to enjoy life and still fly on my terms (and I enjoy single pilot work, flying aircraft that won't mitigate my every error and getting my take-off and landing each hour...) - I would need to find a niche, because as many above have identified - line flying in GA won't work except in few rare cases (ie RFDS).
Therefore, if you elect to return to GA, you can make it work by finding that niche - be it check and training (many of those former dodgy GA operations are being dragged into the brave new world of CAR 217) or pilot management (maybe you would like to be a Chief Pilot who could actually make a difference?). Now, you won't get the same money that the LHS of a 747 would attract, but you can still do quite well - but it is a big challenge to do so. Didn't you say that you wanted the challenge?
Clapped out twins, maybe, but although relatively easy to fly them safely, it is bloody hard to fly them well - and with a variety of types to mix up your day there are some things in GA to cherish.
However, as you no doubt will, weigh up the pros and cons - and do some research before committing to a course of action. You would do well to target some specific GA operators that you would like to make a start with - and see what they say. With your experience, you should be able to sift the BS from those who genuinely try to go about it the right way...