One thing to note is that almost all of the players built into the TV play the video back at 60hz.
This may not be a problem for you, some people prefer their content to be played back at the videos native rate (usually 24hz) to try and avoid judder, most of the time I'm not that fussy.
Again a HDMI cable form the PC usually fixes this as most video cards will output at that refresh.
I have a D8000 plasma and have not really found any problems with MKV playback, subs built into the MKV will work but I don't think separate .sub files do, it will even pass 5.1 back to my receiver using ARC on HDMI.
Edit: Oh yeah I just use the samsung Allshare software on a PC to share the content, I've also used serviio and that worked as well
thanks for feedback...
another 3 hours of instore testing complete.
The 2012 panasonics (LED+Plasma), samsung series 6,7,8, and LGs seem to all generally support
SBS 3D MKV
subtitle selection in mkv (as advised above) - you just have to find it.
functional seek (you just have to find it on the samsung..but it is there.
I found web browsing on the panasonic when using the supplied remote most functional (text entry and navigation)
However both the LG and Panasonic crashed when playing youtube content.
LG fared worst, then Panasonic.
Samsung faired best and did not crash on any websites..but needs a bluetooth keyboard (fortunately the samsung cashback offer means the keyboard doesnt have to cost you). + a keyboard will result in the best overall web experience no doubt (testing a keyboard next visit).
Panasonics support a keyboard.
ST50 dooesnt have freesat....
I could not get mp3 or flac files to show on ps3 media server on panasonic..could not get flacs to show on lg...i have to assume this is user error still...will try again..the manual says they are supported.
So for me, the biggest steal if you dont need freesat and dont expect 100% compatibility with websites, and like plasmas.... is the ST50 - its a bargain.
Panasonic say that html 5 and flash is supported, so hopefully compatibility will get better with future firmware updates...and general web navigation eg to bbc.co.uk is fine (and very functional on the panasonic remote). (as functional as using an on screen keyboard can be).
if you need freesat or 50", the GT50 is still significantly cheaper than series 7.
50 inch £1180
47inc series 7 £1400 but comes with £150 "voucher".
for me though for maximum confidence in codec compatibility i will go with series 7 samsung. Not being able to see mp3 and flacs in dlna on panasonic and terrible experience with codec compatibility 5yrs ago (possibly unfair), just gives me more confidence with samsung.
Series 7 is £220 more, but i because my mate wants one and we both want keyboards we can use the vouchers to ofset the additional cost + apparently better web compatability + it has skype camera + it has some voice and gesture "gimmicks" (im sure).
That said, very impressed with this years mkv compatibility, seek, subtitles and 3d accross all the brands mentioned. (Havent tried sony)