Interestingly enough the transfer speed is probably not being reported correctly but I did get a response from Synology which amounted to try it with a cross over cable to rule out all other network components. Not tried that yet.
Audio Station is fully in place and working which is excellent news - the Mediaserver version is fast whilst the Audio Station library mode is unusable.
I have also now received my Google Nexus 7 (32gb) and discovered that my ancient Netgear Wimax wireless device has a much better signal that the DS213 Air and to make matters worse the DS213 seems to drop the wireless connection when the drives go to sleep - raised another support call as the wireless performance is actually unusable more than a few feet away even on high power mode.
DS Audio on the Nexus is passable but doesn't have either the views listed in the library or the views showed on the media server which is a shame as it makes any collection of music of any size unwieldly, however, several DLNA based apps in Google Play - BubbleUpnp seems to do the job nicely - has a good interface and is responsive. The only problem I've found is that it cannot play to two different destinations (the are products out there that will but the interfaces are unusable) - I'm awaiting a response from the developer to see if the pay for version corrects that issue.
Impressed with the Google Nexus 7, tinkering with configuring it just so will keep me quiet for a while - as expected it has many more options that the ipad offers and it's not entirely intuitive to the extent that I am reading the manual (well, I will read the manual).