Xede is a piggy back but isn't powerful enough long-term- some here already know why, I think. Cobb isn't out yet but it will be a reflash. A standalone ECU is a bad thing nowadays for a modern car- the factory ECU controls way too many things- and to a high degree of precision- that you wouldn't want to replace. Piggybacks and reflashes are the way to go.
CPE has some really interesting things going into a prototype piggyback unit that will relieve the limitations found in its competition (Xede). I think Cobb's stuff will ultimately be the best solution depending on how far they take things, but it can take years to unlock all the parts of the ECU needed to compete with the piggybacks.
The Mazdaspeed's ECU is complicated and has some maps that aren't seen on other cars, and I think there will be a race to see who can either override or replace them first.
So, bottom line: you'll have to wait a little longer if you want a good solution.