For the sake of future reference I am posting this, so I can look back and see if I've lost any weight (from my gear...).
It's currently at exactly 4kg, and I am happy to see other posting their gear weights so I can see if that's reasonable or not.
The core is the Yaesu FT-817ND, with mic., headphones, and Energizer XP18000 battery pack. I have the built-in nicad pack too.
For 2m operation I have a home-made portable Yagi, which attaches to a camera tripod. For HF I have a 20m wire dipole, which is supported by a fishing rod. All of this is in an old utility bag (except the tripod, fishing rod and fishing rod stake, which are a bit long).
I can drop about 300g going with an XP8000 pack, and I should do something with the mic. as it is quite heavy, but all in all it's not too heavy for hiking and it packs quite small.