Yea sure,
Version 3 is in many way better, i can give you the full change log but its a lot.
To enable and disable support i added buttons to the interface, no more typing the tag is unity editor.
Option to create your own materials trough the interface, no more coding it in the existing list.
The data of the asset is now saved in a stand-alone file, and removed the hidden gameobject that was holding the data for a scene.
Extra checks build inside the interface so that setup mistakes are less likely to happen.
Added water areas so you can have multiple water areas at different heights, the buoyancy will detect it and act correctly based on what its in.
Improved the overall code, giving more access to code side of the asset.
Improved the buoyancy calculations so it will not only take less time to calculate it but also less calculations in total.
Better child support, you can now connect/disconnect other gameobject together in run-time and outside run-time, This works without the use of joints.
And many more things, but thats the few things that are improved compared to the old system.
And version 2 will no longer be updated, version 3 will be and im currently working on a better mesh based buoyancy.
Full change list, from version 2 to version 3 and 3.1:
[Interface]
(^) Updated the realisticBuoyancyScript Inspector UI so it works better.
(+) Added a RealisticBuoyancyChildSupport script with nice interface.
(+) Added interface for creating materials.
(+) Added support interface
(+) Added Auto object check for creating objects.
(^) Updated the interface so it looks prittier 
(+) Added sort list by alphabetical and density
(+) Added frindly failsafes within the interface,
(+) Added workaround for the failsafes
(+) Added more information in the settings menu.
(+) Added new interface for the buoyancy and water area scripts
[Support]
(^) Improved the way users enable support
(+) Added Suimono support
(+) Added Habrador support (Build in)
(+) Added better river support for Aquas
(+) Added Ultimate Water System to the support list.
(+) Added extra options in the water areas for supported assets
(+) Added extra options to mix more assets together in a single scene.
(+) Added force flow to suimono support.
[Systems]
(+) Added new script to hold the data of the manager.
(-) removed the hidden gameobject that holds the manager
(+) Use of custom scriptable Objects to hold data
(+) Added some code to check if objects are set trough the interface or not, this will fix issues if setup incorrectly.
(+) Added way of creating a object that can float using code, its simple to use 1 liner.
(+) Added uptomaticly upgrading old system scripts to new system.
(+) Added a static script called the RealisticManager to call common code.
(+) Added a RealisticBuoyancyObjectChildSupport script allowing you to link gameobjects together.
[Other]
(+) New child/parent supprot added, called child sub system.
(+) Added water areas, allowing support for multible support enabled at the same time.
(+) Added more information with each option.
(+) Added more user friendly disable blocks on interface.
[Demos]
(+) Include big boat of users.
(+) Boat driving demo
(+) Water Area demo
(+) Script sxample demo
(+) multible objects demo
(+) Added a player scene demo
