Pex pipes

I believe (if I remember correct) that PEX can expand to 4 times it's size and return to it's original size. It's the only pipe I want in my RV or stick house.

"PEX tubing is a lot less likely to burst if it freezes than copper"
"AND it never breaks in a easy repair spot"

I have PEX piping in the cabin 70 miles outside of Los Anchorage. Having failed to drain the water system completely a time or two prior to Halloween (go-by date for winter), I can attest that both of the above are true...although compared to a break in RV piping, almost anywhere in the cabin is an easy fix spot.

AND it never breaks in a easy repair spot.

PEX tubing is a lot less likely to burst if it freezes than copper, as it's more elastic. It's not completely impossible, but a great deal less likely.

The fittings usually used with the PEX are less resilient and are more commonly the source of bursting due to freezing. The net result is much the same, of course--lots of water everywhere once it thaws if you have the city water connection or the pump on.

Pex won't break but the joints will.

You mean Pex? Yes it will break if water freezes in it and there is no where for it to expand.