This question has been on my mind for quite some time. Although I don't really expect a solution, maybe someone can at least tell me why.
I've been running multiple PHP versions in parallel with
mod_fcgid on webservers for a long time. Unfortunately I always had to compile all but one (the "system version") of them myself. I can do that, no problem. I only wonder why there are no PHP packages from "trusted" sources that can be installed alongside each other. I think running PHP as cgi is quite common these days, so having distinct paths for different PHP versions would seem obvious to me. I can see why big vendors (red hat, debian) won't do that, but why don't repositories like dotdeb (debian) or ius (centos) package their PHP versions this way?