I'm embarassed to say I've never used Marketpress on a project. I probably just know the Jigo/Woo code too well to have branched out - so forgive my feature ignorance.
I've got a client who needs to be able to do custom jewelry orders but I've reached the limitations of the "group product" type.
1. Customer picks a style of jewelry
2. Customer picks the types of beads the want and how many of each.
3. Price is tabulated and the product is added to the cart.
This can all be handled with a group product - right up to the point where a purple bead needs to be available to three different styles of jewelry. Woo/Jigo group products would require me to create the child product 3 times.
It is my hope that Marketpress may have solved this more elegantly.