I am not sold on the 50 deg seat over the 45. I like the IDEA of the 50 more than the 45 for this chamber, but I'm not sure it's the way to go. I've spent more time testing with a 50 than a 45 because that's just where the seat ends up. I usually cut a 45 valve job first then at some point I start wondering how the 50 deg would perform. It's easy to turn a 45 valve job into a 50, but not the other way around. To convert a 50 to a 45 the throat/seat/chamber has to be epoxied up and re-shaped. That's a big deal, so I stay with the 50 deg seat for quite a while.
I have never tried a 30 deg seat. If it were the way to go there would be many people using it. It is almost never used. That's a big clue. A 30 deg valve job will give incredible low lift flow. After that I suspect it would fall on it's face. That is opposite of what is needed. Why make the air turn 15-20 degrees more than is needed? Air doesn't want to turn.