Mikrotik is the only one among cheaper gear to have a PIM (only
Sparse mode) implementation. It is a bit clumsy but with a few tweaks it is (from my experience so far) manageable.
Do you have a description somewhere how you set it up in a 44Net network? We have a national network over here with many (mostly) MikroTik routers linked by radio links and VPNs. It could be an interesting experiment...
Rob