I'll make sure it's compatible with S3 housings too. The thing will be USB-connected, so it might take a header adapter or something to still plug into the boards inside the case but I'll make sure it's possible. S1 and S5, being fairly open, should have no trouble.
S3 to S5 is the same other than the location of the pcie plugs. On the s5 boards the pcie plugs are slightly further apart and a bit lower.
It would be nice to use a s3 cover without any mods but Im sure most would be fine without the cover. Honestly one could just run the plugs in there before they close it up or a jumper cable mounted to the cover. Not a big deal IMO.