Thanks, Ayal!
Experimenting with increasing the VF search space beyond the size of the machine vector for loops with mixed types makes sense to me.
In a separate thread you mentioned that the cost model is inaccurate for some cross-vector trunc/exts. It should be easy to improve the quality of the estimation for the common operations. It should just be a matter of plugging a new value in the cost table that overrides the legalization logic in the cost model.