Well, I couldn't say for sure going from Verizon to Sprint because that would be more of an answer on Sprint's end. However...going from Sprint to Verizon....no, it would not likely work so I agree with the above post.
Basically, some carriers can attempt to flash their version of the need PRL into a phone for use with their "system" however most of the programs from the manufacturers used by carriers "lock" out this capability and are not designed for this use. It is a common misunderstanding that phones need a SW change to work on another carrier however the SW only affects the functions of the handset itself; it is the PRL that determines what towers that phone will read therefore the PRL has to be loaded into the phone to use it on another carrier. You could certainly try it as I have seen it work but these days it is very rare that such is the case.