Nothing wrong with using aluminum tubing for the brake line to the caliper. Thousands of RV's and others do it, and generally without any problems. Like Walt said, a nice loop, and make sure the line has some straight length before connecting to the caliper. That way the coiled part of the tube will act as a spring to absorb the vibrations. Really good flares are important. Make sure if using .035 wall that you dont over flare and thin the wall. We've seen most of the failures by breaking the flares at the base inside the sleeve. The nut pulls everything up tight, but the tube flexes, and cracks develop.
Yeah we make teflon hoses to replace them, BUT we know there are alot of planes the successfully use aluminum tubing in that area.
Tom Swearengen, TS Flightlines LLC
Teflon Hose Assemblies for Experimentals
Proud Vendor for RV1, Donator to VAF
RV7 Tail Kit Completed, Fuse started-Pay as I go Plan