my absolutely very first encounter with kevlar has been this summer, when doing a test for the german tennis magazin i had a set of polyfibre thinergy amongst the candidates. this was a 1.10mm kevlar mains and a multi as a cross. besides the fact that i really did not very much like the feeling of it, i managed to break the mains in less than four hours - and they supplied two sets. simply judging by this, i do sincerely doubt that even thicker kevlar mains would render considerably longer playing times than poly in my case.
i did not have the feeling that in spite of the thinner gauge i was getting more spin, a really rather unorthodox situation, but this could have been due to the fact that the mains were not really sliding back at all, right from the very beginning. could surely be also related to the fact that i had a multi as cross and not a poly, but i assume that with a poly the fel would have been even more unbearable. i have tried some multi-mains/poly-crosses hybrids this summer and have not had any satisfactory results at all.