I just hate the use of Us for the long vowel when there's no actual U sound, so I refuse to use them out of principle. I'd use the line thing if I could remember how to type it. I know it's there, it's not my intention to mislead anybody, quite the opposite in fact. Take a word like Shōnen. I'm not going to write that Shounen because that looks like it should be pronounced Shoe-nen. For me the ridiculousness of the "ou" is why is it a bloody U? Why not an H, or even a W like Shirow Masamune uses? In short, screw romanisation, I'd certainly stop using it if I could bring myself to learn the characters, but I'm far more interested in being able to understand and use the spoken language than the written one.
The accents above or below the letters, every time. I don't know why we don't use those in English. Reminds me of a story I heard about someone who'd been trying to find a station in France and was getting very odd and confused looks. Turns out instead of asking where the "gare" (station) was he'd been asking people where the "guerre" (war) was.It's the same with long vowel sounds. Is it best to represent them with a bar above the letter, or by doubling up the letter itself? In other words, do you respond more to seeing yūki or yuuki? Better acknowledge the extended vowel sound either way, because otherwise you change "courage" into "snow"!
Best not, I'm liable to catch fire.Bless you, @ayase