There are actually two major bugs with the native "SetScale(float akScale)" function.

1) The object/actor affected does not have it's collision box correctly resized. Items made larger can be moved through where they should normally impede (Or be impeded), and items made smaller still block as at their original size. This is especially annoying when part of your dungeon relies on being able to shrink the player down to fit through a small opening (It's a plotline device)

2) Calling it repeatedly (for example to "animate" a shrinking effect) Crashes Skyrim quite often.

These really should be fixed...it's a native function, so it's probably in C++...the collision box problem is probably an oversight, and whoever wrote the program didn't think to make sure the collision information got affected as well, the crashing I can't be sure about, but the native function must not be checking to see if it's already being run before doing it's thing and is causing some kind of data error.\

Oh, and apparently someone at Bethesda recently tried to change something with it...now when you use it on the player, the player autoreverts to his full size...sometimes. That didn't happen a week or so ago when I first started trying to figure out how to get this to work...

So it's effectively gone from "Sometimes broken" to "Mostly Broken."