lol Yeppers, good eye maurtis & copper lines are great in many ways - not only do they look stylie, but they're completely impervious to the alcohol common in today's fuels...
...however I thought I should mention something folks may already know, just in case - the "loop" in the copper fuel line that's commonly seen on boardtracker style bikes isn't just for show, it's because copper "work hardens" & becomes less flexible the more it's moved/bent/worked, including just from vibration. Including the loop helps the copper from fatiguing over time & assists greatly when you need "bend it just a little" to remove & service the carb/fuel tank... I s'pose it may be obvious - but I do not recommend trying to bend such a tight loop as the one in the fuel line w/o a tubing bender, the ones for brake lines are common & inexpensive and you don't need to get fancy, the spring type ones (with included flaring tool) are cheap but work great
Compression fittings are the way to go w/o a doubt & far easier to remove than the press fit of flexible lines, they don't wear out no matter how often you thread 'em on & off again and I've never had one leak - but be sure to get a coupla extra in case you ever need to replace the fuel line itself w/a new one as they are in no way reusable, the little brass compression nubbin is on there for good lol - even if you managed to get it off, it's inner diameter is smaller than it used to be and won't fit over a new line.
I've also used copper lines w/flared ends to serve as conduit, to route the wires from a generator hub to a headlight (mostly for looks) and to run along the outside curve of the rear fender for the taillight's wiring... if you're interested all of my Rollfast pics are here: http://s305.photobucket.com/albums/n...y151/Rollfast/