[Formulajones]

The size of the return is really dictated by 2 things. How long the return is and how big the pump is you're using. The pump size is going to be determined by the HP you're trying to feed.

Most systems that are supplying a very mild engine can get away with a smallish pump and won't need a big return line. Keep in mind if the return is too small you won't be able to regulate the pressure down enough, especially with a good sized pump.

When you get up around 500 hp carburated you'll want a 255 LPH pump minimum. That number changes with EFI pressures. In those situations you might get away with a 3/8 return but I always just do the 1/2" feed and return when I reach this level. It then has the ability to increase the pump for more power later without the need to redo any of the lines. Basically making it a permanent system for any engine that you'll never have to revisit again. The price difference isn't really enough to warrant one way or the other.

You can do the corvette filter/regulator deal, I've done that myself on installs. It's mainly popular because of it's ease of install and it's initial cost is cheaper. It worked fine for me on very stock or very mild setups. If you start making HP there are better ways to do it.
When or if you plan to really get into tuning these things and talking to people like Chris at EFI System Pro, some of the improvements I mentioned above will start to make more sense. For most that just install these things at a bare minimum, never look at anything but the touch screen, and let the system do it's thing, and will never actually see or realize some of the smaller things I mentioned and it will probably run fine for what most everyone is doing.
It's when you really want to dive in with a laptop where you'll find fuel trims and learning and many other tables can be even better with more finite tuning, and having precise fuel pressure is a player in all of that since it's a multiplier in the fuel tables.
If you're not into that, then I'd put it out of mind, let the unit self tune and enjoy.