I know you've been on the fence on this one, but sounds like you want to do it.
I don't have experience with lighter flywheels on turbo cars, generally you'd want a heavier flywheel for a turbo car. How heavy is the stocker? Lighter flywheel will make the car more free-revving, easier to rev-match and more fun to drive, but you also won't be able to engine-brake as much.
I'd be curious to drive a Subaru with a lighter flywheel and clutch, I'm sure it'd be fun.
Been running an ACT Streetlite and Exedy Stg 1 clutch for quite a while now. I also had the same setup on my WRX. I love it. Now, it's be just as long since I drove with the stock stuff so I can't tell you the actual differences. I've only had ~3 misfire CELs over the course of a few years. I am also considering going with a lightened pulley just to see what happens.