You could always just cross it with a good syn gut of your choice.
The benefit to either an Isospeed Classic or a Synthetic Gut is that your tension & playability over time will be much more consistent than any poly. Even the best tension maintenance polys lose their luster over time. MSV co-focus is the only one I tried that remains soft over time, but even that one gets a little too powerful if you don't break it after a few weeks.
What string pattern / racquet do you use?
What's your standard tension?
Head Pro Tour 280/630. Tour Bite 18/Mosquito Bite. Sampras serve, Agassi backhand and Federer forehand. heh heh