Hi Rampage,
Thanks for your reply.
You can buy them both in Germany and UK.
I am only guessing, but since Pineapple runs OpenWRT and the version that I am buying of AP-121u also is - I thought that the firmwares might be so similar that I could easily upgrade through webinterface, or at least through SSH/TFTP....
Hope sombody out there have tried it, or just know.
I also thought about buying a new one, but it will cost me three times the price. That is a lot!