I bought an AMP 11.9, serial n. 0122, and a 8.7 some days ago.
I'm an intermediate rider, 77 kg, board Martin Vari 140x38.
I used the 11.9 4 times, the last time in very gusty conditions and it works without any problem.
After reading all the folding tips problems on this forum, I was a bit afraid, so I spent an hour and half kiting in very bad conditions (from 8 to 20+ knots) to try to reproduce the problem but the Amp was always perfect.
Compared to my 2001 11.8 Airblast (and like already reported from other people), it seems to be more powerful in low wind but I wasnt' able to understand if it has a smaller range in strong wind.
I tried also the 8.7, but only one time (wind 18-25 knots).
I'm using them without bridles (on the Airblasts I used them) on the Cruise position and even if obviously the bar is harder compared to an AB with bridles, it is softer than an AB without bridle, imho a right compromise between comfort and feedback.
The AMP 11.9 seems to be more stable but at the same time more manouvrable than 2001 AB: no jellyfish problem at the moment, I relaunched the 11.9 from water 4 times and it seems easier than 11.8 AB (it keeps the half moon shape, reaching the window edge easily, while the big AB tends to stay flat on the water).
The 11.9 turns better than AB 11.8, the 8.7 is a bit less nervous than an AB 8.4, the two sizes are more similar between them than they were in ABs.
Anyway the more surpising thing is the lift during jumps.
After the first hour with the 8.7 in strong wind, trying to understand how to jump effectively, I made some of the higher jumps I ever made.
It is a strange feeling: the AB has an explosion of traction while the AMP is more progressive and it lift you again and again, it seems to never stop.
Obvioulsy I haven't used them enough, but the first contact seems very good.
Ciao.
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Geppy