Fractured particles and non-actor/non-cloth particles will render fine with motion blur, when rendered as instances. Actors should also render fine with motion blur too. The only time you'll break motion blur is if you convert to mesh and have topology changes. Also I think a final exception to that rule, is that actor animation imported as deformations (not a skin rig) might not have moblur when rendered as instances. I can't remember if I implemented that or not and I can't test right now because the VRay implementation of my dev builds is currently broken (because I'm working through some IPR fixes that broke production rendering code).
The fool proof way to get motion blur on a cache would be:
1) ensure no topological changes over time on anything in the cache
2) place a mesh modifier on the cache (ex: Bend - all settings can be default...this is purely added to disguise the baseobject) and disable GPU instancing/render instancing/vray interface/particle interface in the cache
At that point all renderers should treat the cache object as a 100% mesh with no tyFlow influence or control. It should render with motion blur the same way any other deforming mesh in max would.
And an even further foolproof way would be to create a tyMesher, place in 'input geometry' mode, under particles disable the 'force interface' setting and then select your cache object. VRay and other renderers have no way of know that a tyMesher is a tyFlow plugin (because it doesn't expose the tyFlow interface)...so they would be 100% forced to treat it like a normal, deforming mesh...with all the same rules and conditions concerning moblur.
The fool proof way to get motion blur on a cache would be:
1) ensure no topological changes over time on anything in the cache
2) place a mesh modifier on the cache (ex: Bend - all settings can be default...this is purely added to disguise the baseobject) and disable GPU instancing/render instancing/vray interface/particle interface in the cache
At that point all renderers should treat the cache object as a 100% mesh with no tyFlow influence or control. It should render with motion blur the same way any other deforming mesh in max would.
And an even further foolproof way would be to create a tyMesher, place in 'input geometry' mode, under particles disable the 'force interface' setting and then select your cache object. VRay and other renderers have no way of know that a tyMesher is a tyFlow plugin (because it doesn't expose the tyFlow interface)...so they would be 100% forced to treat it like a normal, deforming mesh...with all the same rules and conditions concerning moblur.