I don't understand the reply from the RS devs, because when rendering as instances the geometry is not being deformed...only transforms are changing. The issue has nothing to do with velocity channels or changing vert counts. Each instance assigned to a particle is a static mesh with no mesh-based velocity information. Note: there are exceptions to this rule that apply to cloth/actor rendering, where instances will have deformation information...but that doesn't apply in this case.
When the particle interface is enabled and all Mesh operators are set to instances, I get a decent render time and the moblur looks fine.
If RS is giving you an error about topology and/or deformations, that means your settings are not correct and you're not rendering as instances. Or you're not rendering with a compatible version of RS.
In any case, the emitter size is irrelevant. Perhaps you're misinterpreting an error about the changing topo of your sliced emitter, as a tyFlow problem.
Attached is what I see when rendering with the latest RS, with the particle interface of both flows enabled and all Mesh operators set to render as instances. As you can see, moblur renders correctly.
When the particle interface is enabled and all Mesh operators are set to instances, I get a decent render time and the moblur looks fine.
If RS is giving you an error about topology and/or deformations, that means your settings are not correct and you're not rendering as instances. Or you're not rendering with a compatible version of RS.
In any case, the emitter size is irrelevant. Perhaps you're misinterpreting an error about the changing topo of your sliced emitter, as a tyFlow problem.
Attached is what I see when rendering with the latest RS, with the particle interface of both flows enabled and all Mesh operators set to render as instances. As you can see, moblur renders correctly.