I would say 5K is pushing it for me but I did spend just over 2k on our 55" and I would say definitely worth it. The screens with no edge are just amazing, particularly when wall mounted. Watching a 3d film its like it's a window in the wall, saying that, I could say that about any film really. Completely different experience. Smart option is worth every penny, size of screen is perfect yadda yadda.
I don't think I over paid for the TV, I got the one that offered the best features for me which happened to unfortunately cost 2k. I do think scrimping on TV's if used a lot by the family is very poor economy. My mate bought an LG with border and went down a size and waster £700 IMO.
If I had enough spare money I might have considered it but it would have to have been a lot of spare money!
What I would say though is get a sound system to compliment the TV. Buying a 5k tv and listening to it on the TV sound is just criminal. Check the Samsung surround sounds as they can integrate with the TV (check the models though) for around £250 for a 1kw set up with discreet speakers. I got one and that was money very well spent. Watching a 3D movie on a screen like this with some massive bass is just amazing.