Call Onecnc and ask to run their evaluation. That should give YOU a better idea of the look and feel of the software. They run there evaluation on a server, you will be given a user name and password to long into the server to run the evaluation. I just called yesterday and I was told there working on getting XR4 on the evaluation server and should have it running very soon.
I have no experience with either onecnc or MC (using bobcad V23 now) but I too have been thinking about purchasing onecnc. I here it's very easy to use and learn + free support no maintenance charges.