full motion or up/down wall mount for Sony W829?

[sansnom]

Why does this seem to be an impossible task?

I'm looking for a full motion or up/down (don't care about swivel or tilt) flush wall mount for my 55inch w829... everytime i find one it says it's only available for small TV's like up to 40" or 15kgs.

Is there something wrong with my search term? Do full motion or up/down motion wall mounts for 55" + TV's exist?

It would be great if it also has a shelf or compartment for a wall mounted soundbar but this is icing on the cake - if it doesnt I'll just fit a shelf to put the soundbar on.

 

[sansnom]

Why do you need to raise and lower the TV?

multiple reasons:
1. not sure what most comfortable height will be until we get a sofa
2. multiple data socket and other wall sockets currently at the level of the TV so it will need adjusting when we start plugging things in

 

[sansnom]

http://www.amazon.co.uk/Wall-Bracket-515-Distance-Höhenverstellbar/dp/B00AFB3AM4

I thought the W829 needed a 300x300 vesa mount?