I agree that the PG6000's look great and the specs are too! Just found what i think must be one of the very first reviews of the TV - at least in the UK anyway;
The PG3000 has a lower contrast ratio (20,000 versus 30,000), 1 less HDMI, the USB port is only for software upgrades (versus JPEG/MP3 playback), 1 way/2 speakers (versus 2 way/4 speakers) and the screen is set in the frame as opposed to the 6000 which has the 'framless' design. If you look closely there is quite a difference in the external look of the 2 sets.
Online the 6000 can be had for only £75 more than the 3000 and i think the extra money is definately worth it in this case! I have found the 42PG6000 for £749.99 delivered ;-)