SA offer pretty much every internal part as a spare, so if anything does go wrong with it you'll be able to get it going again, which is an advantage you don't get with Shimano.

The direct drive thing isn't an issue, as you can get the largest (25t) rear sprocket for the hub and then just use whatever size chainring you need to get the desired gear ratio in first. I'm using a 32- or 36-tooth one at the moment, but I'm considering going for an even smaller one. Technically the smallest chainring you're meant to be able to use with the hub is a 30-tooth, as that's the smallest chainring any SA crankset has, but if you aren't one of those riders who just stands up and cranks to pull away in a high gear, I reckon it'd survive a 26-tooth chainring like the one I've got lying around. I used to be a pretty strong rider, but due to circumstances beyond my control I've lost a fair bit of that now, so I'm considering switching to the 26-tooth one.

The noise might be more of a deal-breaker, depending on how you ride - recently I've had to use lower gearing than I used to (and than I needed when I specced out the bike), and even beforehand I was a spinner not a masher, so I now spend most of my time using the first 4 gears, which aren't the loud ones. First's silent, because the whole mechanism's locked out, and second, third and fourth only use one gear stage each and so only have one set of pawls running. Fifth, sixth and seventh use two gear stages, and have two sets of pawls running as a result, so they tend to be louder. Top gear has all three running, so it's the loudest. If I switch to the 26-tooth chainring to lower all the gears, noise might become more of an issue, as I'll end up using higher gears on the hub more, but I can't be sure.