Anyone recognize this rear shock?
 

<deleted>

I don't recognize it. But before you take it in to the shop, you could open it up to see if you can fix the problem yourself. For instance, Cane Creek air shocks are easily rebuilt, and sometimes only need a bit of grease to make them seal well again.
You could use this to give you a rough idea why and where it's leaking and the sort of things you or the shop would need to make a repair.

This is bad advice that should NOT be followed! DO NOT open up a shock until you know what it is and have some servicing instructions for that unit! Not saying this one does but many shocks have an internal nitrogen charge and things could go seriously sideways in a hurry if you dismantle one improperly.

Let's figure out what it is and go from there. It appears to be a SID Dual Air but I don't think I'm quite right on that. Anyone?

<deleted>

I thought DT Swiss too, but none that I looked at had wrench flats on the upper chamber (which does indicate user-serviceable but doesn't guarantee it for sure). Most DTs have the rebound adjust thumb wheel inline with the shock shaft under the eyelet too. Has me stumped; looked at RS, Fox, Cane Creek (even the old ADs), DT, BOS, Risse, Stratos, even RST. Looking at it again, it appears very KS-ish.