In 1.21f it is very likely that utilities like chiefpaco's mapstat will not be able to be updated to work with the patch, at least until the compression algorithm is figured out. This would make the Domination limit very tedius to avoid, as it would require lots of hand counts of tiles. Accidently triggering Domination would be devastating to a players percent. How should we deal with this?
In games that are meant to play out somewhat quickly, having to figure out the Domination limit and keep track of your claimed tiles would slow things down. If we turn off the Domination victory condition (obviously only when Domination is not the required victory condition), milking gets a 33% boost in potential score, which would (further) imbalance the scoring system.
The initial thought I have is that the MapSize modifiers can be increased by 33% across the board, and Domination turned off. This should keep the MapSize modifiers balanced (or as imbalanced

) as they currently are with Domination turned on.
It also addresses the questions raised by fRisKy to some degree as well. Milking will be further weighted against, not in regards to 'max' per turn score, but in regards to potential overall score. This is because the larger the land area to be developed, the longer the buildup stage will take.
Done at maximum efficiency, I would estimate any map will take at least 20 more turns to build up to max per turn score with Domination turned off (from a point of already owning 66% of the landmass). This is because the average time to double the number of cities is 15-25 turns in practice. You only need to claim half again as much with Domination turned off, so say 7-12 turns for expansion. It will take at least that much more time to build up the needed improvements with gold in what amounts to a totally corrupt 33% of the map. And then the fastest that a city will be able to grow to near max size (after an Aqueduct/Hospital are built) will take another 6+ turns. The last couple pop points taking considerably longer.
It isn't a big increase in weight against milking I admit. Probably only a % or 2 in practice. Any other ideas about how to deal with 1.21f's lack of a useable tile counter to avoid Domination? The other option that comes to mind is to allow reloading if and only if it is to go back a turn before Domination is triggered, and to not trigger it. This can still be somewhat tricky as well though, as often 1 turn back will only be able to avoid domination for so long. An unsellable culture producer (small or large wonder) near the coast or unclaimed land could eventually claim the tiles regardless of what the player did (short of disband that city). Disbanding the city could have a large effect on score if it were the JS Bach city or Cure for Cancer city for instance.