My setup is Synology DS212j -> WD N900C -> 5Ghz | 2.4Ghz
Surface RT connects to 5Ghz by my choice, and via Desktop I watch movies with no lag.
Acer S3 on 2.4Ghz, via Desktop with no lag.
HTC Windows Phone 8S and HTC One V clients on 2.4Ghz using DS Video (Synology client) with no lag.
$60 Android tablet 512MB RAM on 2.4Ghz using DS Video with no lag.
Therefore, I am not complaining
I can't say the same thing when using DLNA/UPnP via MediaMonkey or PowerDVD Mobile.
Problem is: While Streaming over DLNA is fine (at least with tested 720p), watching the same material via the Explorer produces stutter/dropouts. I've been watching the task-Manager and it seems there's no constand steady streams, instead there are peaks in bandwith to fill the buffer. I assume that the wifi isnt fast enough for this mode. The reason for not using DLNA all the time is the lack of mkv support in DLNA enabled apps and vice verca.
I'm streaming HD content from my NAS. Typical size from a movie is 20 GB (transcode from blu-rays which i own). With 5MB/s i get a lot of stutter and playback problems. Works perfectly on my NB over Wifi (15 MB/s) and of course on my desktops over my LAN (1 GBit).
For a smoothly playback from HD content i need 10 MB/s. Which shouldn't be a problem if the Surface would take advantage of 802.1n.
My Surface Pro is by the far the fastest wifi device in my home. I happened to be still tweaking my wifi network when my SP arrived, so I went to the trouble of going to various areas and connecting directly through my router on 2.4 and then 5 GHz, and then connecting through the repeater. I did this with my smartphone, my Playbook, Ipad and with the SP and the SP literally lapped the field 3 times over. It was also very useful because it runs Win legacy apps like inSSIDer and Advanced IP Scanner on a mobile basis. Maybe there are ways to do with an Ipad, but I could never find the software in that damned, vaunted App Store.