Hi,
Reason 9.5 is still in Beta, so some things may still change and VST support is brand new. Reason has been an unsupported host in all other versions, so I think the simple (and perhaps boring) answer must be that you have to try it.
They claim that all VST 2.4 compatible plugins that are not MIDI players/generators will work in version 1 of their VST implementation, so we *should* be good to go.
I'm looking forward to trying it myself.
BR,
John