I have the stock flywheel out of my 06 WRX, but it has 80k miles and needs resurfaced. Assuming it can be resurfaced, it'll be about 5 pounds lighter than your dual mass.
I went with an ACT Streetlite in my WRX. It revs up quickly, but is still heavy enough to avoid CELs and stalling issues. Other than OEM,
It's cool; I'm with the band