Old topic but, I've recently had to deal with some trial and error with my JLF's. I use it for both 4-way and 8-way games.
I agree that the octagonal resitrictor is the best compromise if you're playing both 4-way and 8-way games. But as with all compromises, it's not really optimal for either 4-way or 8-way.
The best way around is to use the standard square gate for 8-way, and 4-way by rotating the core piece 45 degrees. As far as I can tell this gives proper 4-way, with no way of hitting diagonals. The problem is switching between 4-way and 8-way, because the restrictor plate has to come out so that you can turn the core piece. It has two prongs sticking out of it, but it's fairly impossible to rotate it without taking the whole plate out. And to do that, you'll probably need to open the cp and access it properly from below.
I've modified my restrictor plate so that I can easily flip from 4-way to 8-way by simply twisting the centre piece of the restrictor plate, not having to use any tools or remove the plate or anything. This way I can just reach up from the coin door and make the switch between 4-way and 8-way.
What I did was I just filed down some of the plastic between the two holes that locks the piece in place, so that it locks into position but still can be rotated without any hassle. Probably done by many before me, but still my best mod ever.
