Funny thing is, when I first discovered that 45 degrees was not climable I thought that it was a bit shallow (I mean, I could easily do it, but I can't run at 90mph
). However, I just got used to it. Like all parameters, I suspect most experienced mappers have checked the limits of movement (eg, checking the lowest wall that will block the player for both walking and jumping) and then mapped to those parameters.
Anyway, the map fix turned out to be a lot simpler than I feared it might be. I'm all done now, aside from testing it a few times to check that I didn't miss any important blocking lines and, perhaps, checking it against a newer exe just in case anything I have done gets messed up by the change back of the rounding - if that happens.