Over here mate we had several differing types/styles
I have been in a nice position in that I could try most of them over long periouds of time
So Air Treckers (aka CZ series or Exo's over here) verses Powerisers
Firtsly the old powerisers had good springs and a good frame as far as the older styles went
The second generation (The one with ballrace bearings and cuffs) got a bad name over here for falling apart
This assuming you are talking of PoweriSers not PoweriZers they were two different beasts
The newer style stilts (CZ/Exo/Air Treckers) had a few problems to start with and a few ongoing issues with some suppliers
First the new type hoofs (all rubber with the nuts molded in ) are far superior to the old style that had an ally bit with the rubber bolted to it
They last a reasonable time and give good grip but are quite expensive to replace (hence I screw bits of motorcross tyres on mine)
The bracket at the rear of the foot breaking has been cured over here with a beefed up bracket and I havn't seen one break for a long time now
Springs are always a sticky point but I believe the Cz are the best springs that have been made to date (and that includes Powerskip springs)
They give very good response and I can get more height with ease against the older types of springs
As for springs breaking I am rather heavy and have in the past broken a few springs having used both types I would recon that the new CZ springs are less prone to breaking that the older ones and that is reflected over her in one simple way
PJ offer a 3 month warrenty on CZ springs and they only used to offer a 1 month one on the older types
Bearings on both types of stilts tend to wear out after a while but there are several ways of making them last a lot longer (gluing them into the housing works for me )
So to sum it all up the CZ/Exo/Air Treckers are a no brainer win for me
Jason