Thanks Daz, that's really helpful. 
I've just renewed the top 3 sections on my Extreme, they all snapped at some point and I've cut a few inches here and there etc and re-fixed (bodged up).  Hence I renewed all 3 sections in one go. 
I think the Extreme pole is good but when you go side to side across the top of a window, you can feel it's on the edge of stability and you hear the odd little crack noise; especially if you work fairly quickly. 
I'm cutting out all my awkward jobs now, so my round is fairly easy; I could go for something slightly heavier, but more durable. 
I think I might try yours as my next pole.