For me, I'm on the same wave length as vin.
If we are in this for the long haul, and dont have a super dooper retirement plan that means you can retire at 50..... Then use the lightest and most rigid pole you can afford.
Even if you think it's easy work with an slx, I guarantee that in 20 years time you will feel it in your joints. Even with an extreme your going to feel it in your joints, but surely it's got to be better and worth a few hundred quid?
I did a conservatory roof for the first time with my extreme and noticed a major difference. No shoulder aches what so ever.
The £100 a year that an extreme pole costs me is pennies (literally pennies day in day out ) in comparison to minimising repetitive strain and injury.
Granted if you only work part time or less then the need for an extreme is less too, but still well worth it in my opinion.
My dad works with me and I'm getting him an extreme pole for the same reason.
Extreme 18, 25, and 47 is what I'll have by the end of the year and for me they will be worth each and every penny.