I did a search on this and did not find the info. So if it is out there and I missed it, sorry, please direct me to it.

I am currently running Di2 with a Shimano "7900" SRM (the one with a 7800 crank and 7900 rings). I am going to go to the new Dura Ace 9000 and I am not sure if my current crank/rings will work or not. I would run a full 9000 group, except use my current "7900" SRM. I dropped SRM a line to see what they thought, or what they might have in the works. I have not heard back yet. I do not think Shimano is going to make 11 speed rings to fit a 7800 crank, but that would work. I spoke to Shimano and they said it will not work, but the guy on the line did not sound like he really knew.

So what do you all think? Have people done it with Campy 10 speed on one of their 11 speed groups? Any advice or insight would be appreciated.

Thanks.

Yes I have used 10 speed campagnolo crankset on 11 speed campagnnolo gruppo. No problems!

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I suspect most of the pro teams already running 9070 will have the same set up until SRM (or Shimano themselves maybe) sort something out i.e. Sky, OGE etc.
Have a look at some of the images coming out of La Vuelta and you might spot something.

Video in Shimano's FB page shows Degenkolbs won Vuelta stage w/ 9070 Di2 + 7900 SRM.

If the 11s Shimano chain is narrower than 10s version, I would guess it might affect front shifting a little bit, but IIRC the 11s chain is the same as the old one widthwise.
Either way I think you'll be fine.

+1 to what antifocus said
I think it wouldn't be a matter of compatibility, simply one of slightly compromising performance. Good luck and let us know how it goes though!

I use my SRAM SRM on my 11sp Super Record, no issue.

Given the scarcity of DA 11sp this question is a little hard to definitively answer...

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As has been said, yes it will most likely work with a slight compromise in performance. Also keep in mind it might rub slightly on the big chain ring whilst in the small ring on the bottom of your cassette. It wont cause anything to happen you will just hear an anoying metalic rubbing.

Thank you to everyone who replied. I went to FB and looked at the Shimano video, so that was a good spot and why I asked on this forum, you guys know your stuff. All the answers are what I assumed they would be. As was pointed out, the groupo is not out there much yet, so no one has direct experience. I saw one of the groups last week at the USA Pro Challenge in town, but it had the new crank.

Once I try it out I will post back on here.

So I asked 2 different Shimano tech guys during Interbike and both of them said it won't work. The first tech guy simply said they aren't compatible when I asked him why. The second guy said the narrower 11s chain might stuck in between 2 rings and that's why the small ring on 9000 crank is closer to big ring. I also asked SRM people the same question and they told me I should ask Shimano.

Anyway I ran 11s SR w/ a 10s Record crank for a year w/o any issue. (campy also moved chainring closer on 11s). Therefore unless DA 11s chain is significant narrower which I doubt. I see very little compromise running DA 9000 w/ a 7900 crank. Well I could be wrong and can only find out after putting miles on the combo.

Installed a 6700 compact on a full DA 9000 mechanical equipped bike yesterday. (also compact) The combination worked flawlessly w/o even touch of the limit screws. And yes I tried my best to drop the chain without success. No chain rub in any gear. I'm very confident that my SRM 7900 crank (53-39t) would work w/ the new 11s group very well.

That's reassuring to hear. If I go to DA 9070, I would like to not have to change out my 7900 SRM.