If your thinking of a pole to be used day after day window cleaning then I'd say the slx, it will be much easier on the body and easier to use also having a shorter close length. The powerpole will almost definatly out last the slx though. But after using the slx you wouldn't want to go back to an alloy or gf pole.
Simon.
I do have both poles and they both have good uses. For every day window cleaning I prefer the SL-X as it is less strain on my body (though plenty of people manage with it just fine). I found that the Powerpole was fine until I needed to use it at difficult angles. The flipside of this is that the Powerpole is cheaper and I suspect will last longer. So a few pros and cons to think about. There are times when I need a beefier pole like the Powerpole. Indeed, if I'm working on a particularly windy day, I find the extra weight of the Powerpole a plus.
Whichever pole I'm using, I still find a short pole such as the Ionics 2 x 2ft better for ground floor. The SL-X can be used for ground floor - even in some tight spots - but sometimes on a hard slog, I just want something even lighter for ground floor work (so long as it can reach).
I don't think it's possible to say definitively which poles are best as a lot depends what type of work you have and how fit your body is. I'm even findingf that the SL-X has reduced my ladder climbs onto flat roofs still further as it can be used at long length at awkward angles without busting a gut.