I've installed silverstripe since seeing your post here t'other day about it... I don't like the back end much, but should prob get used to it enough to see what it will actually do.
What are your thoughts now you've had a few days to play with it?
I actually quite like the back-end now I've gotten used to it, the only thing that annoys me is the load times for it, even on a local server.
I like it. Making the "skins" for it is a piece of piss, as are add-ons/plug-ins/whatever-ma-jigs.
Don't think it's quite ready to replace ModX yet, but it's certainly got potential, especially with the underlying php framework.
I recommend installing the blog add-on, because it lets you have a play about with some of the other features, like widgets etc, without having to faff about too much.
Oh, and the modx add-on I referred to is no longer available lol, so guess that rules that one out, although there may be other alternatives!