I had a couple burst copper lines (from the previous owner) anyway I "repaired" the sections with clear braided neoprene tubing & stainless clamps. The tubing comes in various sizes & fits right over the copper lines.
Has anyone tried this before, it seems to me it would work about as well as PEX & i can keep the original copper valves. According to the web site its FDA approved.
Heres a link to the hose, although i bought mine at Lowes.
PVC Braid Reinforced Hose Tubing