Getting ready to book internal flights in southern Africa on Comair, and noticed the "features" state: "ONE piece only. Max weight 7kg. Max dimensions 56cm x 45cm x 25cm (22in x 18in x 10in)."

I assume this is cabin baggage (although it doesn't state that), but 7kg is awfully light for a standard 22 X 18 X 10 rollaboard; my 'ultralightweight' weighs 3.5kg empty! Is this actually enforced; i.e. do they routinely weigh the carry-ons? If they do, and I am over the weight limit, do they gate-check it (like American Eagle) where you get it back at the other end without having to go to baggage claim? Is there any additional allowance for oneworld elites (sapphire)? Does it matter if my long-haul flights are in BA in J, although not booked on the same itinerary?

I searched the forums but only came up with posts that were > 2 years old, so hoping for more current info...