RE: Top Flite 1/7 P-51 Build
Ian:
It's not that the E-flites are incompatible with the Robart Robostructs; if you want to pursue that solution you'll have to make some compromises.
The E-flite retracts come stock, with 5mm wire struts. If you wanted to fit 3/8" Robostruts directly to the retract, you'll have to drill out the hole in the trunions to 3/8". This will undoubtedly void any sort of warranty, and will leave you with thinner walls for set-screws and general mechanical strength. The other approach would be to drill out the Robostrut to accept a 5mm wire stud. I think the Robarts are sized for 3/16 wire, 5mm is just slightly bigger so this would probably not affect the mechanical strenght of the strut leg.
You can also go look at RCSkylite.com. They have metric sized robostruts for p-51's and P-47's, and have 5mm studs. I don't know about the scale looks, or overall quality (yes, they're Chineese built, but so are the E-flites), but it's an alternative.