Doesn't the new auto complete and the plug-in SublimeCodeIntel do the same thing? One of my concerns is that say you are using a plug-in for a feature that is later implemented into Sublime, now you haven't read the what's new so you have no idea. What happens then?
Not the same.
The editor itself supports almost all file types with basic auto-completion.
SublimeCodeIntel supports a few scripting languages with more intelligence.
SublimeClang doing same smart job for C/C++/ObjC.
It's just based on your work pattern to decide which one to use.
For me, all 3 of them are all very useful everyday.