I know that in one of the more new Minecraft updates, many of the features of Soul Sand were removed or altered. Namely:
You can no longer make one way doors with Soul Sand (or chests, and a few other blocks).
Soul Sand is no longer usable as a dock for boats, as the boats now break on impact as with other blocks.
I believe the feature where the walk speed of Soul Sand with ice underneath is is EVEN SLOWER than ordinary Soul Sand has also been removed.
As I understand it, these features were seen as bugs, since they were initially not intended, but were never removed with most updates (most of these bugs/features have been around since the Halloween update that introduced the Nether), so they were removed with one of the more recent updates.
My question is, What is the newest version of Minecraft that still has these features associated with Soul Sand?
I'm asking because the majority of an adventure style map I made had a bunch of traps and puzzles but is basically broken without these features. I'd rather not take my game back further than required to fix these specific issues with the map in question.