Alu does all sorts of strange things with repeated hitting, but it does stiffen with hitting thus compensating for any tension loss up to a point.
Main thing a poly cross needs to do with gut is (1) remain stiff enough to stop the gut from trampolining and (2) let the poly slide. PTP isn't really that type of string for (1). Best as a full bed (or possibly as a main). Best when fresh as a PTP stringbed seems to get softer over time.
Last edited by Torres; 11-14-2012 at 12:37 PM.