Dunno if anyone can say that better.
The only time I ever say don't go 20v is when you already have a 16v installed, The money you spend to convert it is better spent on the 16v.
If you go 16v do the bigport and do it properly, JDM manifold etc.
If you do a 20v follow the path Matt has done with his, I don't know of a better example of a 20v to this date, Everything is made to make the engine work properly in a RWD setup.
A smallport feels good because of the low down torque pick up they have, smallport heads are very restrictive and I have worked with one where everything was done for hi hp and the engine still only made 120hp @ the wheels, I said numerous times to my old boss that the bigport head is far more better for power but he didn't wanna change.
I am pretty sure from Brad and Matts input that you will be able to make up your mind quite easily.