What exactly does OpenGL NG offer that you are going to take advantage of that is not currently available in the latest version ( 4.5 ) as of this post ? There is alway doing to be driver overhead, unless you have direct access to the hardware...most of the technique to lower driver overhead and whatnot is currently available in the latest GL version..My silly advice to you is to learn the API first instead of waiting for features that you may/may not use.
There really isn't a lot of information out right now, but the next generation OpenGL initiative is a ground-up redesign that [paraphrasing] aims to streamline the api for easier use and implimentation, act to unify and bring modern GPU access to all platforms, provide a standard intermediate shader format for greater portability of shader programs, provide enhanced conformance testing methodology, provide explicit application control over GPU and CPU workloads, be multithreading friendly, greatly reduce CPU overhead and provide full support for tiled and direct renderers.
It will not be backwards compatible with the old specification, which has been bulking up for over 20 years, and that's really what I'm trying to ask - is it worth learning at this point? I've read a lot of criticisms of the current specification (see: http://www.joshbarczak.com/blog/?p=154 and http://richg42.blogspot.com/2014/05/things-that-drive-me-nuts-about-opengl.html ), and they're not alone it seems.
As someone who wants to work with primarily the modern parts of OpenGL (for both computing and managing lots of data asynchronously), it's difficult for me to parse through what's an old part of the specifcation, what's newer and a better practice, what examples are using pure legacy code and should be avoided, what extensions are available and what are appropriate to use... the books that I can find only go up to OpenGL 4.3 but there are some major additions to the core profile in the past few years (direct state access, buffer placement control, efficient asynchronous queries, efficient multiple object binding, flush control...) that I could see causing significant changes to how someone manages their project. I've been reading through the sixth edition of the OpenGL superbible, one of the most up-to-date references I could find for getting started (published last year), and it's still hard to trust the format that's provided.
I understand that I wouldn't _have_ to read the entire 800+ page specification, but at the same time I sort of would. At the end of the day you really don't know what you don't know and with something that's been around as long as OpenGL has and is as quick of a moving target, it's difficult to trust what you're doing without going through the entire spec first. If anyone knows a trustworthy and well up-to-date and informed source for learning, including the current best practices, that would be super helpful.