I'd prefer they not have both Manufacturers and Nations on the same day. It really irritated me when they announced the Supra Cup (I'm all for even more competitions, for variety sake) and then had the races on a Saturday on top of the two existing competitions.
When we're in the middle of a proper season, twice a week racing even when only doing one of the competitions does feel like a significant time commitment. I'm not sure how some people manage both.
I guess one of the benefits of twice a week racing is that if you can only commit to one of the days then that can still work out. If it's only once a week on day you can't do, then the FIA's are not an option for you.
Not sure where that leaves my vote! I'd just like to see races spread out through the week a bit more