That's actually pretty good for 16" wheels, but heavy for a 7. I second the recommendation of Goodwin Racing - they're good people to deal with. They are a dealer for 949 Racing 6UL wheels, which are highly regarded in the Miata community. Reasonably light, strong and cheap - made for a Miata racer who didn't like the range of choices for 15" wheels. You can get them 7, 7.5, 8, 9 or 10" wide. I have a set of the 8" wide ones for my track tires on the Miata, and they've been perfect.
I too saw the GRM article, which confirmed what others have discovered at autocross - if you have a choice between weight and width, go for width. That said, wheel/tire weight will have an effect on ride and feel, and a 3 pound difference is a significant percentage of the weight of a 7.