Only problem with the high temp silicone is it adds dimmension to your tolorences ! and can add up to .004 of an inch , not really that good for the back cover , this is why I recommend using the anaerobic sealer, it doesn't add much if any dim. and seals and cures instantly ! it may seem wet on the outside, which is great ,you can simply wipe off the extra ,as it cures with the absence of air ,hence the "anaerobic" in it's name.
Silicone works perfect as well , but doesn't look as professional