keep in mind though your scouts led by that termie sergeant will no longer be able to infiltrate!
and to really hammer home to point about just how silly you can be with the 'sicons' trait, it's perfectly legal to have a termie sergeant w/sniper rifle who can move & fire?!!
sure it would be a cool conversion and all, but it just goes to show you how stupidly broken the marine codex really is! (ie; it's a prime example of why the 2 authors who wrote the 'dex are no longer games designers!)
cheers!