We have added mpls-test and routing-test packages to the download page. They extend the functionality of already existing packages in the areas of MPLS and BGP. Please test these new packages:
http://www.mikrotik.com/download.html
It depends on system architecture - x86 does not support BGP in level 4, but RouterBoards do support. Wether BGP is allowed or not at any level, does not affect MPLS, but essentially you need level that supports BGP if your setup requires BGP (MPBGP).
sorry, fixedlinks are again broken for the beta test packages for the 400 series??