I've been looking at both of these packs and was hoping to hear from others who have used them. They both seem pretty similar in overall volume, pocket configuration, price, weight and suspension systems with each having removable stays and a pad pocket.

But, while the Starlite seems to have a close suspension system to the MP, it isn't exact. It seems like it can be customized a little more with the addition of load lifter straps and it has those great pockets on the hip belts.

But the Mariposa Plus is slightly cheaper and it included a small pad for the back, while the Starlite doesn't. And you can customize the bungee straps on the MP.

While on paper the Starlite and Mariposa Plus seem to have similar volumes, the Mariposa Plus and the Comet are actually closer, see the photo comparison in this test:

http://www.backpackinglight.com/cgi-bin/backpackinglight/gossamer_gear_mariposa_plus_backpack_review.html

If you aren't in a rush, Gossamer Gear says they are coming out with curved stays, and a few other changes to the Mariposa, sometime this year.

Myself, I chose the Comet, and like it a lot: good volume for me, comfortable suspension, and real, not bungee, compression straps, which I find to be key when going frameless.

I've got the Starlite and used it this summer for a 7 day trip on Isle Royale and using a prolite 3 for my support it handled
29# with no problems.