They are worth it on many planes, but most of my planes have fixed gear now days. I usually keep at least one plane in the hangar with retracts.

The ones I use were designed and machined by myself back when I did CAD-CAM work for the Gov't (Your tax dollars at work ) I haven't found anything on the market as good (and sorry, all of the sets I have are spoken for), but here are a few tip I would suggest.

1) Avoid using them for Trike gear. Main wheels are a big enough hassle without having to deal with a steerable nose gear.

2) Buy the sturdiest ones you can find. Make sure that they have at least a 3/16" gear wire, and try to find one that you can drill out to accept up to a 1/4" gear wire just in case.

3) Use the smallest wheel possible (Easy if your runway is paved, no so easy if you fly from grass), and make your wheel wells as big as possible. Try to get at least 1/4" of clearance all around the wheel. Take offs and landings will bend the gear back so you need room to keep them from sticking in the wheel wells.

4) Check them after each flight and straighten them if necessary to prevent them from getting stuck in the wheel wells on the next flight.

They are definately extra work, and I wouldn't want them on every plane, but they DOOOO look SWEET!