I guess in general I'd lean toward 'only use them if there is no other way'. but I'm also a realist.

I don't know who/what brands are out there, but in general I'd tend to want onee that have an inner diameter that mounts them snug (and therefore in perfect alignment with) to the hub, and then have an extended sleeve/lip/hub section so that the wheels are also still perfectly centred to the hub via the centre, not a 'close but possibly a few thou out' fit relying on the studs or long shanked mag wheel nuts.

You could always get spacers that don't feature the above stuff, then turn a couple of sleeves up on a lathe to insert/locate the spacers and locate the wheels too.