Awesome news
I tried it on a recent small game I'm working on, which only contains regular Sprites, SlicedSprites, and TextMeshes, and has a single SpriteCollection.
When I updated the package (not sure if the previous one was v1.7final_patch2 or v1.76final_patch3 - how can we check the installed 2D Toolkit version?), I got a bunch of warnings but then everything worked ok, both in the editor and in runtime.
Problems arose when I tried to add Platforms. I added both a 1x and a 2x, keeping 1x as Current Platform. As soon as I pressed Commit, I got a bunch of these errors: "Unable to find platform specific texture '[MyTextureName]' for platform '2x'", which are all about 2x versions, and none about 1x. After that, when I select any sprite in the Hierarchy, I get this repeating error (coming from the Inspector's GUI):
IndexOutOfRangeException: Array index is out of range.
tk2dSpriteThumbnailCache.GetThumbnailTexture (.tk2dSpriteCollectionData gen, Int32 spriteId) (at Assets/TK2DROOT/tk2d/Editor/Sprites/tk2dSpriteThumbnailCache.cs:46)
tk2dSpriteEditor.DrawSpriteEditorGUI (.tk2dBaseSprite sprite) (at Assets/TK2DROOT/tk2d/Editor/Sprites/tk2dSpriteEditor.cs:62)
tk2dSpriteEditor.OnInspectorGUI () (at Assets/TK2DROOT/tk2d/Editor/Sprites/tk2dSpriteEditor.cs:11)
UnityEditor.InspectorWindow.DrawEditors (Boolean isRepaintEvent, UnityEditor.Editor[] editors, Boolean eyeDropperDirty) (at C:/BuildAgent/work/d9c061b1c154f5ae/Editor/Mono/Inspector/InspectorWindow.cs:888)
UnityEditor.InspectorWindow.OnGUI () (at C:/BuildAgent/work/d9c061b1c154f5ae/Editor/Mono/Inspector/InspectorWindow.cs:243)
System.Reflection.MonoMethod.Invoke (System.Object obj, BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture)
EDIT: though reading again about Platforms, I suppose I misunderstood how they have to be used, so it's not a bug?