+1
New Variant suggestion: 5-check KOTH

Getting your King to a middle square before you are checked five times would be too easy.
Wouldn't that be harder than normal king of the hill, where the goal is just to get your king in the middle at all?

You can always clear blockers with Queens and pieces.
Well if they block the middle with pawns and you throw your queens and pieces, they still have their queen and pieces to keep your king from coming in. Even normal king of the hill is not that easy, IMO.

This would basically be a slightly risker KOTH. I would expect the gameplay to be very similar, probably not sufficiently different to justify a separate variant.
The thing about 3-check is that, properly used, a queen can always get two checks, and a rook often can too: one from a distance, and then a suicide check that sacrifices the queen. That means that, to win, you only need to get one other check, and then find an opening for a queen to safely deliver the first check. Your opponent, meanwhile, is trying to prevent this happening. As a result, every game is on a knife edge where either player could make a single mistake and suddenly lose. It's sometimes worth sacrificing a piece simply to get a check, because it forces your opponent to play much more defensively..
5-check significantly reduces the risk. Now, instead of one check plus two with the queen, you need five. It's no longer worth sacrificing a piece to get a check, and getting put in check once is no big deal.
I would imagine that the gameplay would be very, very similar to regular KOTH. Only rarely would the threat of a fifth check start to significantly affect the gameplay.
3-Check KOTH, on the other hand, might be more interesting. You're combining the high risk of an instant loss of 3-check with the incentive to push the king forward into danger. However, I think the 3-check aspect would dominate.
4-Check KOTH might be a more balanced way to combine the two variants.
Basically 2 player chess but first player to get their King to the middle, deliver 5 checks or mate wins.