I currently use nant, ccnet (cruise control), svn, mbunit. I use msbuild to do my sln build just because it was simpler to shell out.
Are there any merits to switch
Nant has more features out of the box, but MSBuild has a much better fundamental structure (item metadata rocks) which makes it much easier to build reusable MSBuild scripts.
MSBuild takes a while to understand, but once you do it's very nice.
Learning materials: