Just as a head's up to everyone...I thought it worthwhile to mention this here to save others some potential problems.

I downloaded the 1.9 beta yesterday to take a look. I'm currently running @110 mods, inlcuding the unofficial patches for the dlc (not for the main game), SKSE and SkyUI. My game had been bug free, running smoothly, and following the installation of Dragonborn dlc had not had the animation bug where your character goes stiff and is semi-crucified (also effects melee animations - sword swings).

Now, Beta 1.9 does not work with SKSE, which I anticipated, so I could only use in a non-SKSE session, which I did for about 10 minutes.

However, on exiting and rebooting through SKSE, I had the following:

The Courier appears, naked. This was the first time this had happened to me. The animation bug came back with a vengeance - affected not only my character, but the Serana npc follower as well.

I can't say for certain that there is a connection between Beta 1.9 and those bugs, but it's too coincidental not to be. I've run everything through TESVedit again (had a couple of mods that needed it), and I've run a couple of FNIS checks to see if that sorts out the animation bug.

They supposedly fixed the courier bug in 1.9, so it's odd that you still have it. I've had it with about 95% of my couriers, so I'll have to see if I still get it with 1.9 once it's out. (Modding, so I can't do much with the beta)

The USKP is currently not compatible with 1.9 Beta
There is a new SKSE version out for the beta however.

Besides that, I have non animation bug and the curiers I met until now had full clothes on with 1.9 Beta.

Just took a quick peek at the FNIS page on the Nexus, and it looks like the author hasn't updated the mod for the 1.9 beta yet. He got an update out really quickly after Dragonborn was released, so hopefully he'll have an update for the 1.9 beta out really soon as well.

SKSE has a 1.9 beta update out already, as noted. I haven't had a chance to try the beta yet - I'm currently playing Morrowind, and still have tons of stuff to do there. I'll probably just wait for the beta to go final, and for the modders to update their projects, before getting back into Skyrim.