I've been using plain ol' double-walled automotive fuel hose for around 40 years, and I've never noticed any swarf in the float bowls (and I run Mikunis, which have no inlet screens).
But, I change hose frequently, I'd say every 1-2 years. At $.35 per foot at the auto supply store, why not?
BTW, if you don't like the writing on the hose, a little acetone or alcohol will take it off.
'65(lower)/'66(upper, wheels, front end, controls)/'67(seat, exhaust, fuel tank, headlamp)/'70(frame) A65 Bitsa.