Don't upgrade if you need to use the Lightning HDMI / VGA adapter!
Unfortunately, b2/b3 doesn't at all support the Lightning-HDMI (and, most probably, the Lightning-VGA) adapter. This means you will NOT want to upgrade if you need to use the Lightning HDMI / VGA adapter. Stay with 7.0.4.
It displays the following error message upon connecting the adapter (screenshots taken on my iPhone 5):
(original:
http://www.flickr.com/photos/33448355@N07/11967960084/
While, under 7.0.4, the adapter is properly recognized. A screenshot of General > About, with the adapter listed at the bottom:
(original:
http://www.flickr.com/photos/33448355@N07/11967537225/ )
Under b2/b3, the adapter isn't even listed there.
And this is the detailed view (again, in 7.0.4 only):
(original:
http://www.flickr.com/photos/33448355@N07/11967827413/ )
This applies to both b2 and b3, both with JB and without. With JB, I've tested the fully spoofed 7.1b3 -> 7.0.4 spoofed case too, in addition to the non-spoofed one. It didn't help either.
Incidentally, it's worth noticing Apple haven't released a
single firmware update for the HDMI adapter ever since it has been released - that is, for 1.5 years. Hope they won't completely abandon it. That would be disastrous for many Apple fanboys defending the inferior quality of the adapter by stating it surely will be fixed in future updates. An example of these fanboy (in this case, he's "
gaussian blur") Lightning-HDMI- and Apple-defending posts, from DPReview, is at
http://www.dpreview.com/forums/post/52607824
(Originally posted at
https://forums.macrumors.com/posts/18644744/ )