Here's the output on the console while I'm typing in some text into a text field which has type="email" prop on it.

We had a similar problem before which we discussed over at issue #22
So I'll investigate it one more time.
I've spend some time to track this down and this turned out to be a React regression. Here are my results:
0.14.8 OK
15.0.0-rc.2 OK
15.0.0 3x
15.0.1 OK
15.0.2-alpha.1 OK
15.0.2-alpha.2 OK
15.0.2-alpha.3 OK
15.0.2-alpha.4 OK
15.0.2 OK
15.0.3-alpha.1 OK
15.0.3-alpha.2 OK
15.1.0-alpha.1 OK
15.1.0 OK
15.2.0-rc.1 1x
15.2.0-rc.2 1x
15.2.0 1x
15.2.1 1x
15.3.0-rc.1 1x
15.3.0-rc.2 1x
15.3.0-rc.3 1x
_(1x - one warning, 3x - three warnings, OK - no warnings)_
It's clearly a regression in 15.2.0-rc.1, so I've tried to see a diff between 15.1.0 and 15.2.0-rc.1. Then I learned, that React is not tagging their release candidates, so I've tried to diff 15.1.0 with 15.2.0. Well, it's something _(it may freeze your browser)_. I don't really know, what to do now.
Wow, nice work!
And I think these two are somewhat relevant to our case, the latter probably solving our case inadvertantly
https://github.com/facebook/react/issues/6441
https://github.com/facebook/react/pull/7333
Yes, kind of - I've even referred to them in my issue facebook/react#6992. Hope it will help (and get merged asap).
I'll close it for now, as it's not uniforms issue.
I've added a note in README about it.
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So I'll investigate it one more time.