Max,
While there may be some degradation in gain from using stainless
steel, would it really make that much difference? I think the 'biggy'
is that you already have the stainless steel and would have to find
the aluminum. Maybe the next 'biggest' thing would be making
electrical contact between sections of that steel? A tenth of a dB
loss just ain't no step for a stepper...
- 'Doc

(all puns intended)