There is no difference in main-software between an H and K models.
There is only difference in 5000/6000 models (2 DRAMS) and 7000/8000/9000 models (4DRAMS) and there is difference for Italy and the 21:9 models (Q5553)

3D will not be better with any software update for these sets (crosstalk will exist) this is due to the speed of the panels and not the Philips Hard/software. The 2k11 models have a faster LCD and a scanning backlight so crosstalk will be as minimum as can be.

Someone said something about sharp usb timeshift, hahaha sharp, yep they make good microwaves.

HDMI audio drop out? that is mainly caused by cheap garbage you connect, not respecting the spdif format fully. You should use PCM output, wich most manufacturers support.

If you think you want to downgrade for any reason, don't go below 140.34 and don't use 140.37. 140.40 is one of the best.