So i've been told by different people that both types of pipe can be used for not only hot and cold water and UFH systems. I've given to understand also they both use compression fittings. 

 

Does anyone have experience with plumbing either whole houses or normal remedial work, using these different types of pipe? Seems like the general benefits are speed of connections and maybe lightness of material? Am i missing any others, and also are there any significant negatives, aside from those which might arise from misuse/poor handling?

Ability to change and modify is the issue with press fit - they also use bespoke fittings. 

An issue in what respect. I sort of picture in my head a length of copper pipe and a length of each of those and with the requirement to run something off those feeds, each one of them will need to be cut, a fitting added, and a new run of pipe added. Why is that more of an issue with a "plastic" pipe than copper?