I use the top 4 sections of an extreme (so 20ft) as my everyday pole for absolute lightness and a bit of reach over an 18. It has lasted me 20 months so far and at 18 months I gave it a thorough clean and new tapes and it was working well.
At the same time I bought new clamps as I had heard that people were replacing them every two years or so if they are their main working pole and I have just put them on with a new Gardiner Ultimate Dupont brush and it feels like new again.
For high reach I have an old style extreme 47 which I have had for over 4 years now which is great too.
Having used SLX's as my everyday poles I would agree with Daz and think that hi mod extremes will wear quicker than SLX's. The new Phantoms are an unknown quantity at the moment but we should know when users have had them a while - what is the availability of spares like?