Another alternative for very high quality mechanical retracts is available from [link=http://www.einziehfahrwerk.de]www.einziehfahrwerk.de[/link]
There are several sizes available as well as different retract geometries. Here is a link for the 18 lbs ones, [link=http://www.einziehfahrwerk.de/ezf-100.htm]link[/link]. The end stops are fully adjustable for zero play and they are very strong.
I normally fly off grass fields and have had no problems whatsoever.
The really nice thing is that custom legs, be it oleos or piano wire, are available at very reasonable prices.

/Red B.