I have seen very few actual flowbench test results with CVH heads. I do know that Cnc Heads certainly does use a flow bench to develop their port profiles - which are then digitized for use with the 5 axis cnc machine. Complete flow test resuts are very important.

Flow bench test figures by themselves do not guarantee performance increases.
However, one can map port velocities, as well as port swirl ( flow bench attachment ).
For low rpm use (and emissions and economy) maintaining high swirl is a benefit.
For high rpm (performance) use the opposite is true - swirl does not aid power production,
in fact the fuel starts to separate from the air-fuel mix resulting in much lower power output and high BSFC.

We have been developing a CVH head here in Canada. There are a few areas that are very responsive to major flow increases without much material removal. This cannot be done without the aid of a flow bench. The port has a high velocity areas, and low velocity areas.
It is quite a complex port to get right.

I have attached a pic of the head we started with. The protruding valve guide was made flush with the port since the picture was taken.

The inlet manifold must also be worked on. No point working on the head by itself - the inlet manifold is part of the inlet - major power improvements can be made here.

Love to see others results.