Has anyone tried this? I mean export lets say a cube from Maya as .obj, import it to Houdini, affect it in any way, with skinning or modeling, or deformers and export it back to Maya again as .obj, and use it in Maya as a blendshape (morph target whatever)? Will vertex Id (order) stay the same or it requires some mumbo-jumbo back in Maya?
Of course while importing exporting we will not delete vertices of polygons...

Dejan Njegus
Will vertex Id (order) stay the same or it requires some mumbo-jumbo back in Maya?

as long as you don't scramble the point order in Houdini by the operations you are applying it should stay the same

Well thanks a lot! I guess the next question is how do you accidentally change the point order (most common way)? Last night I tried some basic skinning with a couple of bones and everything went fine, will muscles affect point order (I guess they shouldn't)? I'm thinking about creating some kind of temporary facial rig with muscles for creating series of blendshapes for use back in Maya, they don't have to be perfect, lets say 70-80% of precision, so the artists could sculpt them just a tad to a desired state.

there is a lot of common things that can change point order and since Houdini setups are very flexible it's hard to say whether muscles will change point order or not
You can easily setup a muscle system that will not change the topology as well as one that will
but in either case it's usually easy to make sure the output mesh is just deformed input mesh even if it means it's point deformed in the end with the simulated mesh or something along those lines