Do it! That PEX is extremely durable. And if you're not comfortable as it is... 1/2in PEX will slip right inside 3/4in PEX... I did that on my storage building at the bottom plates.
I haven't tried it, but there's videos out there that test PEX's capabilities... Such as freezing water, letting the pipe swell, then watching it shrink back down when ice thaws.