Over the last couple of years I've been lucky enough to be a regular SLF, and I for one would pay more for comfort, but only to a point (i.e. I can't afford business class!). An extra £50 on long-haul I would gladly part with.
The difference in pitch on the different 'classes' of airline is very noticeable. For example, I've been very comfortable in economy with CX and DL, yet recent trans-atlantic flights with AIH and BY were, quite frankly, horrendous. Like being in cattle trucks.
For most passengers on these charter flights, however, it's probably their one trip into the air per year, and they'll happily suffer discomfort in order to save a few quid. These flights are always full, and that speaks for itself. Noticed a lot doing exercises, though...
Must credit both Easyjet and Ryanair while I'm here, as I've always found them both comfortable (albeit on short-haul).
Heading back to the original post, I wouldn't imagine that increases in pitch and seat size would make a huge difference in a 300+ mph crash. Runway incidents / fires, yes.
But as already metioned in this thread, we as pax have to accept to a degree that business is business and 100% safety can never be provided due to economic constraints. I, for one, have faith when I board, but a bit of extra legroom never goes amiss!