You might have more chance of a response if you post in the mechanical engineers pipeline forum, but you may also get more input from someone like ITP who make this and have experience on their website. AFAIK, PIP is normally reeled from onshore facility onto a reel vessel. Wet buckle you'll find out if the pipe weight suddenly increases.... Snake lay is sometimes used to take out the issue of inner pipe expansion versus outer pipe, but is subject to issues of concentrating stresses after a few cycles, i.e. S lay can become Z lay.
Repair in deep water - forget it.
As said look at vendors and instalation contractors like allseas, subsea 7, technip etc google search, Institute of marine engineering lectures, papers from internaitonal forums.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way