As Patrick did, I'll speak only to my hub, the Sterling Replicars hub:
I believe it was made to replace the standard hub, so no change in length. No play in mine, either. The only safety issue I could think of was well covered by Patrick
! You need to pay attention when replacing it to make sure it seats properly and clicks-in.
For quick wheel swap, you would need an extra mounting ring, but you could easily swap it out by removing the 6 screws that hold the wheel to the hub ring... not much longer.