I also use the MSF naturals in place of foundation- but it really depends on how much coverage you want. I know some people like to use the MSF naturals together with SFF- to set it, or to provide more coverage? I'm not sure which. Perhaps a bit of both?
I know for sure that using them both gives some serious coverage.
I have actually found that the MSF natural, with a spirtz of fix+ can actually make your skin look dewy in a very subtle kind of way
As for the shimmery ones- gorgeous
They can all give you some kind of 'glow' I think- it really depends on what you're wanting to use them for, what your skin tone is like and so on
(i.e. Global Glow as a bronzer... Northern Light as, or over blush (once you go and tap the glitter off lol) etc. )
If you're wanting to find a MSF to use AS a blush though, I wouldn't really recommend the newer ones much. The older ones (Petticoat and Stereo Rose) are the main ones which will show up as blush without you having to layer... and layer... and layer at the risk of appearing too frosty to get the equivalent colour payoff. (Meaning if you're going for the new pinkish MSFs... it's best to try them over blush to give you the glow you're looking for).
Not a MSF- but worth a thought... Try Lovestone MES as a blush! I LOVE it
Glowy too.