Sometime soon I'm planning on switching over to Subversion for all my projects. To give you a sense of how big a task this is, heres my list of active projects in Eclipse:
With the exception of the LWJGL library projects these are all 'active' projects - ones that get compiled and run frequently, and I end up adding or changing code in most of them. So I'll need to back the whole thing up, import each project into a subversion repository and then fix the inter-project references, build dependancies and other gubbins. And if I want to keep both versions working at the same time (a safety net if it all goes horribly wrong) I'll need to arse around with separate Eclipse workspaces too.
It's the inter project dependancies which I fear will give me trouble. I have no idea how I'll have to treat them differently if everything is from subversion rather than sitting on disk next to each other. Just something I'll have to take a step at a time I guess.
I don't even know what format and layout my repository(s) is going to look like either. It's the kind of decision I hate - you've got to make a decision really early on, yet without using it before you have very little ideas of what is a good idea or not. Worse, it's a pain to change later so you're left cursing the bad layout forever more.