We are now using the Turnigy DST-700. Compared to the earlier 2213 motors, it has a lower Kv rating (700 vs. 800) which is a better match to the prop, the axle is threaded which allows us to directly mount the props to the axle, and the front and rear bearings are the same size which makes it nice if you want to swap out for stainless or ceramic bearings.
Hubert and Robert:
Although the 2.6 and 2.7 look the same, there are very few parts in common, so it's not really feasible to upgrade from one to the next. If you have a 2.6 and its almost fully built, I would consider upgrading the vertical propeller to the 2-bladed racing prop style as was shipped in the last batch of 2.6 kits.
One could also upgrade the internal electronics, either by using the new controller board with the existing E-chassis, or by inserting the whole 2.7 e-chassis into the 2.6 vehicle. The 2.7 e-chassis is the same overall size as the 2.6 and uses the same DB-25 connector.
We should have 2.7 controller boards in the store soon, as well as electrical and mechanical (cut files) documentation for the 2.7 design.