I looked a bit more into the possible arguments to keep DHE alive once you support ECDHE and you only expect traffic from endusers with a real browser (machine2machine traffic with access from obscure libraries is a different matter). From the SSL Labs checks we can deduce the following components that support DHE but do not support ECDHE:

• Android 2.3.7
• Java 6

Windows XP does not support forward secrecy at all, and all other browsers beside IE (except for the first Chrome releases) bring their own TLS implementation.

A very interesting data point is the cipher usage graphing provided by Wikimedia you can find on this dashboard. Currently I see roughly 4% of connections to be negotiated with some variant of a DHE cipher.

That is after all not much, so I'm tempted to disable DHE for HTTPS where I've working ECDHE support soon. I'd first like to gather some stats from the BigIPs which I'm babysitting but that unfortunately is not that easy. As far as I can tell the only option is to insert a header a via an iRule and log the header on a backend system. Or you can setup HSL and log directly from the iRule.