macromedia flash flash remoting:

There is always the chance that macromedia will stop supporting the product as
they did with generator. And it already seems to be on the way out, since they
are not promoting it at the max conference this fall. For a developer,
investing time in learning server side macromedia products is risky,
considering their track record. Otherwise, I love remoting and have found no
significant disadvantages other than the cost and rather shotty documentation.