Well, we've got the #2, which sits in the corner of our pocket patio (I'm not even sure it strictly meets the guidelines for a real patio. But, describing it as a ground-floor balcony might give you an idea of how big we're talking). And, I'm not sure if it's actually allowed, but the management here seems to be fairly laid back about some things.
It helps that there's not a huge amount of smoke that is released to waft about the place.
The reason we have the #2, is because we
are in an apartment, and our stick burner (a Pitts and Spitts barrel pit, with offset firebox and an upright at the other end) is currently living with friends, as we have no place to put it, let alone use it. So, we go and visit it occasionally. The pic below is from the last time we used it, which was last Labor Day.
So, we really needed the SI!
Prior to the P&S pit, we had a CharGriller, our first pit, with offset firebox, which my sister got when we moved from California to Texas ... we also had a couple of Weber kettles, an 18" and a 22" ... my sister got the 22", and my son got the 18" - he's also the one that got our original copy of Smoke and Spice.