Oh lord, Kyo would have way too much fun at CCS!Syaoran's expense :-). The poor lad isn't as tough as Sasuke, after all. But Yuya would pet him and make a great fuss over him (yup, cue more blushing). Hm, now that we're freely mixing mangas: why do I get this strange feeling that Kyo would be rather taken with CCS Tomoyo, though?
And they'd all watch the Shinrei Vs Hotaru via ballet devolve quickly into a sibling death-match! You're right, Shinrei would take it sooo seriously, and then Hotaru would flounce in and show him up, not a scrap of discipline in evidence (and then get distracted by a caterpillar).