New build Plumbing

The plumber my daughter employed for installing central heating and reversing the hot water flow used copper pipes and copper pushfit, with occasional soldering.

I expect they use pushfit because it's quicker. There may also be a ban on hot work on site to reduce paperwork, especially where stud walls are involved.

There's also copper pressfit. About as quick as pushfit but more compact in boiler rooms etc. Also in larger sizes (28mm etc) pushfit gets expensive.

Theo

No; if it's your build. do what you like. But I dare say some building sites insist on no "hot works" for RAMS/insurance reasons ...

I've used a few copper pushfit at radiator valve elbows, mainly for appearance as they're on show. Seem unlikely but so far they've held.

They look good but IIUC they do need an expensive tool (£1000+) for installation, and a fair bit of space around the fitting to use it.

That said, if I could solder I would. Looks better, cheaper, and at least seems as if it would be more reliable than push or press fit.