I've seen multiple people complain about the change in water physics, and with the amount of bootcamp maps forced out of rotation as a result of this I can't really blame them. With that in mind, this would possibly be resolved by expanded options for water in the map editor, both by allowing you to rotate the grounds and letting you set the density, buoyancy, etc to a custom degree.
Since spiderweb ground already exists in the game as a modified variant of water, I doubt there are technical limitations against this either, and it would generally allow far more variety in the game's physics if this were implemented.

Density is one thing that creates buoyancy, so you would just need to be able to increase or decrease the density of water.
I think we need to be able to see the properties of modified water because if a modified water looks just the same as other water grounds, that can lead to trolling or a confusing map.
People will probably think that "Cheese in water good" or "Cheese in water bad" and with different maps with it, it will take a long time to adjust and even then it does not look good.

Maybe the water could get a darker tint every time the density increases. So a density of 8 would be darker than a density of 6.

/no support

The main reason I made the distinction between buoyancy and density is because of how the spiderweb ground works in terms of horizontal as well as vertical movement through it. I would expect buoyancy on its own to affect only vertical movement, with or without cheese whereas density would be something that makes it more difficult to move through the water in general.
I can't imagine any confusion with regards to water properties to be any worse than that which already ensues from customizable restitution, especially with tramps and lava and whatnot, not to mention the people who stick things like collision and soulmate options into maps that aren't designed for them. My impression is that most of the maps that don't customize water effectively would essentially be weeded out from rotation by the P0 category, and eventually removed from it entirely. Overall, as with customizable restitution I can see more good than bad coming out of making this an option.

/halfsupport