No, it does not really work. But it depends on the use case. The following are my observations:
MC17 & 18: MC as DLNA server, more or less any iOS app as DLNA controller, iOS device as DLNA renderer: search and pause works.
MC17: MC as DLNA server, plug player iOS app as DLNA controller, DENON AVR4311 as DLNA renderer: search and pause does NOT work
MC17: MC as DLNA server, 8player iOS app as DLNA controller, DENON AVR4311 as DLNA renderer: search and pause does work
MC18: MC as DLNA server, any iOS app as DLNA controller, DENON AVR4311 as DLNA renderer: search and pause does NOT work
MC18: MC as DLNA server & controller, DENON AVR4311 as DLNA renderer: search and pause does NOT work
My conclusions:
As soon as you use a separate renderer (e.g. Denon) things start to get difficult. As can be seen with PP and 8player (under MC17) some apps can control the renderer properly, others cannot. It is hard to say if the apps or Denon is doing something wrong (i.e. not fully in line with DLNA specs), but my assumption is that Denon is the bad guy.
Unfortunately MC is also having difficulties with Denon (and maybe others) as renderer. Even if this is the fault of Denon, I really do think that MC should be able to handle Denon properly. As 8player showed with MC17 it is possible. And I would consider Denon as a company far to important to ignore their appliances.