I only just got a stringing machine a month ago and boy have I been doing a lot of testing. I've done a comprehensive Multifilament test and the X-One and NRG2 came out on top, with the surprise being Sensation which I also really liked.
As for this thread though, I'd used Champions Choice in the past in my BLX 90 racket and while it was very good, the durability was very poor in my opinion. So I thought that given I was stringing my rackets, I thought I'd try a few different things. I had my first hit out with a Poly/Gut hybrid tonight and wow - loved what I had put together. I used Klip Legend 16 with Luxilon BB Original Smooth, using string savers in the Federer pattern, as well as power pads for the gut (using a BLX Pro Open now). After hitting for 2 hours with it, the wear was minimal (MUCH less than X-One Biphase 17), and the power and control was very good - definitely better than Champions Choice IMHO.
I think the important thing was to get the tension gap right. NG likes to be strung at very high tensions, due to the elasticity. At the Aussie Open, Clijsters was stringing her full gut setup at 66lbs, which is at the top of the tension range for her Babolat Pure Drive, and Henin was around 62lbs - also near the top of her Wilson tension range. But.... Poly's like to operate at a lower tension.
Having consulted the threads here, and asking a bunch of questions, I ended up stringing my BLX Pro Open with the Gut in the mains at 63lbs, and the Luxilon BB in the crosses at 55lbs. 8lbs may seem a lot, but I think it kept the operating range of each string where they ought to be. The power was amazing, with very good control and feel too. I'm definitely a convert to a hybrid setup!
I'm going to use the leftover string to put in another BLX Pro Open racket that I have, to put the Poly in the mains, and the gut in the crosses, to see what it feels like. It seems to be a personal preference as to which way people like it - Andy Murray uses a Poly main with a VS cross and he seems to play alright. ;-)