I have the MDS 48 and have been flying it on a Twist for the past year. I bought it used and it was way out of tune when I got it. Did some carb adjusting and it has been a pleasure ever since. Excellent power, easy hand starts, completely reliable and prefers low nitro fuel. From all the information I have seen about the .68, it is the best of the bunch from MDS; better power than the .78. I am looking for a .68 to buy cheap, because everyone knows MDS are crappy engines and are no good.