Here's an old photo of a 901 - 60mm, long curved arm, band attached below the brake lever - on my Streetmachine (comedy cutlery is because we were doing voodoo ergonomics to work out how we could adapt gear controls for barkata's hand disabilities):
The long arm brings the mirror up high enough that your wrist doesn't block the view.
I've since replaced it with the 80mm 903 version, which gives a better field of view, at cost of sticking out a bit more.
If you're careful in how you arrange the band and the split in the socket that clamps to its ball (this will make sense when you fit one), it will fold most of the way in without too much trouble, though repeated folding and unfolding does mean the socket screw needs tightening every few months. Both this and the ball-in-socket at the back of the mirror are stiff enough to stay put, but loose enough for ease of adjustment, so the mirror will move when bashed rather than being damaged (I once had the mirror pop off the arm when the bike landed on it in a crash, it went back on with a bit of force and worked fine for several more years).
I don't lean my bike against walls habitually other than when fully loaded (where the rear pannier is the contact point); I tend to just use the stand. I do fold the mirror to make it easier to fit the bike through front doorway at the start and end of nearly every ride, though.
General consensus is that these are surprisingly durable (mine have certainly had plenty of abuse), though I've heard that the plastic quality may have declined in more recent production. The weak point is the band-on attachment, specifically its grub screw. I recommend a decent bit of old inner-tube under the band, so that it stays put better without having to do the screw up bastard tight.
Most people's complaints are vibration and small size related, both of which seem to be mitigated by the suspension and riding position of the Streetmachine. (I tried mounting a 60mm one on the kingpost of an ICE trike, and it was shaky enough to be completely unusable. I've fitted a pair of 903s to a friend's city bike which has 40mm tyres and a suspension fork, and they've been fine. I expect the average rigid upright is somewhere in between.)