Yes, you can use the audio input feature to mix and match if you wish, but I'm not quite sure what sort of plugs you want to use with MIR that aren't 64bit already. A bit bridge is a recipe for disaster, IMO, and I'm glad that VSL hasn't wasted time on trying to create one. You could always use J-Bridge if you really need to use 32bit plugs in the 64bit server.
DG