Some info on Binsor's advantages, particularly in comparison to XML:
Maybe DSL is taking it a bit too much, though. It is a single class that has some fancy sticks in it, and a lot of Boo magic
Looking at the age of those posts, Binsor doesn't seem to be the newest project on the block. I assume that some of the techniques in Binsor (if introduced there) have since been applied to the Windsor Fluent Registration API as well:
http://docs.castleproject.org/Default.aspx?Page=Fluent-Registration-API&NS=Windsor
I would assume by default that since Boo is a less popular language that the Binsor API is less frequently updated.
I suggest checking into whether Binsor is still updated. If it isn't, I'd ditch it in favor of the general .Net API. If it is still updated, I'd take a good look at both options. Binsor has a potential to have better Boo support, since the Fluent Registration API was designed with C# as the top priority.
Disclaimer: I am not directly involved with the Castle.Windsor or Binsor projects, and I have only skimmed the Boo documentation a few times out of curiosity. Most of this info I've gathered from some minor Windsor experience (with the Fluent Registration API) and from Google - I'm making a lot of assumptions.