Benefits of Unity Sprites vs. NGUI Sprites

[Yukichu]

I started watching the videos on NGUI 3.6 on youtube (excellent so far) and there was a large bit about using Unity Sprites instead of NGUI Sprites, and how you could almost get the same draw calls and how to use the automatic atlas builder, etc.

So, I am wondering... what are the benefits of using Unity Sprites with NGUI Widgets?
Are they faster?
They don't seem to be less complex as you stated in the vid the draw calls would be harder to get down to the same with NGUI.
Do they use less triangles or something?
Handles in memory better or some such thing?
Is the atlas builder better, more efficient, handles larger sprite sheets more reliably... or something?
Do they consume less memory?
Anything else?
Will this 'ease' the transition over to Unity GUI?

I like the idea of options.  Is there a good reason why I shouldn't change all my NGUI Sprites over to Unity Sprites, besides that it'd take a bunch of time?

[ArenMook]

They don't use less triangles, memory, nor are they more efficient. It's simply for convenience -- you don't have to pre-generate your atlases beforehand, and you can also effectively end up with several atlases. The transition to Unity's GUI should be easier though, since it also uses 2D sprites for everything.

I personally advise sticking to NGUI's current approach if you're used to it. It's certainly more predictable when it comes to optimizing draw calls.

However if you're doing a 2D game using Unity's sprite system for it or want to share the sprites with other tools that use 2D sprites... you may find the ability to create your UI from the same sprites an advantage.

[Yukichu]

Makes perfect sense, it's what I thought but just wanted to confirm this.

Thanks!