RE: Diamond Dust retracts
I see only 1 reason to even consider putting retracts in a Dust: you've only got a tarmac strip to fly off. If that is not the reason, then don't bother. A Dust is a very light plane... the lighter it is, the better it flies.... try to keep it that way!
I have had two Dusts so far: one Webra .32 powered one, and a Jett .50 powered one. I had a lot more fun with the Webra, just because the plane was so light. The lighter airframe allowed some VERY aggresive flying... it was not blistering fast, far from it (120 mph tops, with a BIG maybe)... but I could do the most insane moves with it within the "field perimeter" at an average speed of close to 100 mph... and that was fun!
So keep it simple and light... it will reward you when you do.