The Dave Brown and Spring Air retracts both go way back to the old days in pattern. The debate over mechanical vs pneumatic will probably go on forever. I personally don't like to have to "pump up" the plane out at the field and like the gear to remain up during transport, but those are just personal quirks. Both work well w/ careful attention to the details. The Dave Brown retracts were originally designed by Ron Chidgey and sold by Pro Line, then Southern R/C, then Dave Brown.

FYI: Learned one thing about retract servos recently. I have the JR low profile servo in my Hangar 9 Mustang 60 and it works great. Found out though, that you cannot use a 5 cell receiver pack with that servo. I thought at first, I had purchased a bad servo. Phone call to JR gave the answer. I tried both with and without a Radio South voltage regulator. When used w/ 4.8 volts, it works fine. I have Futaba's low profile servo in my Tiger Tail, and it works fine on 5-cell pack. The JR servo has more advertised torque.