No, you can't patch Classic to Gold. If you want reasons to upgrade, I can just post the latest History.txt, but I might run afoul of post length limits!
Seriously though, what do you get?
-Lots of little interface enhancements that you soon won't be able to live without (build queue multi-add, mousewheel support,
-Fewer bugs!
-More possibilities for modding and what kinds of mods you can play (see all the excitement over the Research and Intel generating components?

)
-Less chance for Malfador to go out of business and not make SE5!
I'm sure others can come up with more answers, as there have been a LOT of these threads around ever since SE4 Gold was released, and I must say as time goes on my investment in the game has only become more valuable as more patches, mods, etc. are added to the Gold Version that those without it are missing out on!

(though there shouldn't be any more patches, but hey, they've got to stop some time

)
edit: wow, 5 people replied while I typed that!

well OK I also got distracted and had to help my brother with his math homework...
edit: well, 3 of them were the same person...
[ March 04, 2004, 01:40: Message edited by: Ed Kolis ]