I've been using the upgrade that has been available here at Avsim for quite a while, the one where you have to manually change config settings. Is it worth downloading the official upgrade from this unofficial one?

If you're talking about the "update" that's available from simflyer.net, then I would say definitely grab the official Flight1 update.I installed the FS2002 version a few weeks ago into FS2004, and it flew well enough that I never saw the point in adding the simflyer update, but I was all over installing the "real" one when it became available. The first thing I did after that is apply the modification that Uwe R. did to replace the 421's GPS with the payware RealityXP 530XP. Works great! What I did is un-install the FS2002 version of the 421C, and then I installed the full new version rather than the update file - the full one is a bigger file but then you're assured of getting it right the first time rather than wondering if any changes that were made to the old one will hose up the new version.Dave Blevins