Have used ITCI at Hong Kong MTR and never had a problem. Very useful service if you can't get a late check-out. IIRC it's also available at Kowloon as well bit I've not used that one.

I'd certainly do everything poss to get a late checkout not least as if memory serves there are no showers at the BA lounge at HKG ? Either that or I was too p*ssed to find them last time....