I think that it is easier to find a load that shoots well with a good gas checked boolit than it is with a plain based boolit. The plain based boolits have the potential to shoot very well. It sometimes takes a lot of load developement to find a load that shoots well. I can sometimes find a good load quicker with a GC'd boolit than a plain based boolit. Of course, of my last 3 Mountain Molds I had made, one was a gas checked, and 2 were plain based.
I think as you push the velocity, the gas check becomes more important. However a lot of boolits, especially heavy for the caliber, seem to me, to take more velocity to shoot well.
I think the gas check helps compensate for "everything that is not quite perfect".
Another very important factor, which I don't think any one addressed is "What are your accuracy standards?" With a revolver, some people are happy with 2 1/2" groups at 25 yards, some want the same size group at 50 yards, and some want the same size group at 100 yards. What is good enough for you?