As you may know, I'm a big fan of poly/poly hybrids. I started mixing them after reading this article of TWU, where they noticed that polyester is usually the slipperiest cross string, and that strings tend to be slipperier in combination with other strings than with themselves( of course, it says about differente materials, but I've found out that it also works with poly/poly hybrids ). In my YT Prestige MPs, I used to play with PLII 1.15 x Focus Hex 1.10, around 41/39 lbs. Yes, the round string on mains and the shaped string on crosses. I did that because PLII gave me the best feel, and Focus Hex tamed a bit of the power of the PLII, especially when it started losing tension. Poly/poly hyrbids are great for this: you can mix the best points of 2 different strings, although sometimes it doesn't work as you expected. And from all the poly/poly hybrids I've tested so far, it seems that the best combination is a round string + a shaped( not twisted ) string. I have also noticed that a thinner string on crosses works better, because it seems to make the stringbed more uniform, giving a more predictable response while playing. It also makes the stringbed a bit firmer, and I assume that's because tensioning thinner crosses is easier so the difference in tension between the mains and crosses is smaller. Now in my IG Prestiges( customized to the specs listed in the sig ), I found out that shaped strings( pentagonal/hezagonal ) work better on mains. Yonex Poly Tour Spin was my first try, but now my current go to string for the mains is B5E( I'm also planning to try Tour Bite and BHB7 ). I was using Focus Hex as the cross string, and although the performance was very good, the combination B5E x Focus Hex started hurting my arm a bit. So I started trying other crosses: my first try was Firestorm 1.20( I have a reel of it ), and although it added a lot of comfort to the stringbed, it also lost the initial characteristcs very soon, adding too much power. It also wasn't as slippery as I thought. So, my next try is B5E x Yonex PTGP. PTGP is very slippery, and has an oily coating, so my expectations are high. I hope it adds comfort to the stringbed while keeping the control, and letting the mains slide freely over it. I have a 1h hitting session tonight and I'll hit exclusively with the racquet strung this way. I'll update you guys later about this stringjob.