Fuel line size
Oh don't get smug now, RRR probably doesn't even realize that his comments completely epitomize everything you were just saying. But don't think for a second he'll ever admit he just totally proved your point, even if he does eventually realize it.
As for the fuel line situation. Most PTFE lined -6 AN hose has an internal diameter of ~.320", which is pretty much the same as 3/8" hardline (3/8" is the OD of the hardline, not the ID which is closer to .320"). Personally, I would still use as much hard line as is practical. Not because the braided line is going to leak or anything, PTFE lined hose is pretty tough stuff. But it's still synthetic material, and it still has some kind of life span. Eventually it will get brittle, or break down, or even possibly react with some new fuel additive sometime in the future. If you've pulled old rubber fuel line off a car you know it doesn't last forever (yes I realize PTFE is not 1970's rubber hose). Now maybe none of that happens for a long time, maybe even longer than your car is going to be used which makes it pretty moot. Maybe it's overkill, but I know the stainless hard line isn't going to get brittle or deteriorate with age, and nothing should react with it. And unlike the stock steel line it won't rust, assuming it's really stainless.
There's also a pretty big pressure rating discrepancy, just looking at Summit's numbers the max operating pressure for their PTFE lined braided hose is 2,000 psi. Which is a lot, but their 3/8" stainless hard line is rated for 6,000 psi. Now both of those are totally overkill for fuel line that only sees 4 to 7 psi in a carb system. The braided PTFE lined hose also has a max operating temp of 400*F, which is a bigger concern. The stainless hard line will withstand much higher temperatures without failure, and there are definitely things kicking around under the car that get hotter than 400*F. Not to mention what happens if you do have a fire for some reason.
Anyway, those are some of the reasons why I prefer hard line myself, and that's why I ran stainless hard line on my car with the flexible braided lines only at the ends. I know you won't be the only person to have run stainless braided -an hose from the tank all the way up to the carb if that's what you choose to do, but personally that's not how I like to do it.