If you check the books and manuals for Li-Ion and LiPoly the authors will tell that both have
a theoretical limit of up to even 20,000 cycles and no memory-effect etc, but then they explain
how those numbers get down to 100 or less and talk a lot how the wear-off occurs, calling it or
not memory-effect. Capacity of every battery goes down faster with the higher currents you use.
Surely there might be some capacity even after 500 cycles but the duration fo the flight might be
about 1/10 of the first flight duration. I guess your friend does not just decide like that to stop
using those batteries after 300 cycles, isn't it. He is forced to stop using them because they
have no more capacity of any use.

You did not mention a price, but here is what I see to be very discouraging even after several
years of Li-euforia:

http://www.hobby-lobby.com/katana50.htm

That thing needs Two - PQ33003 PolyQuest "Twenty-Five" 3 Cell 3300 mAh 11.1V LiPo Battery
Pack @ $ 119.90 ea., which makes $ 239.80 and that is for 0.5 engine similar performance.
Thus for 0.91 perfoamnce the price might come badly to about 500 USD or more.

And even if we say that the Controller and motor jointly are similar to price of OS.91 then the
price of the smart charger is comming on top with about 200 USD more; any fuel pump is only
below 20 USD.

One liter of methanol is about 0.6 Euro and one liter of castor is about 2 Euro per liter all from companies
which use them to make their main prodictions. Surely it is case without Nitrometan and I do not want to
put money to the pockets of the RC-Shops for fuel. It is lot cheaper outside of them.