Revamp lens setup considerations

Some of you may have seen my recent threads asking for opinions about changes to my lens setup - including going into Nikon...
I've now decided to settle down with Canon and would like to maintain a setup consisting of one super telephoto (500/600) + 300mm 2.8 IS + 70-200. I shoot mainly birds but would happily take photos of any mammals that come my way (my dream is to go Alaska/Africa!). As for birds, my favorite subjects are terns/other seabirds, raptors, kingfishers, bee-eaters and waders and I love to do action images of them. I do shoot some of the small birds if I come across them but static shots of these are not a priority.
So now my dillema is whether to swap down my 600mm to 500mm and get some cash back for a 300mm 2.8 without investing too much additional money. I am at a stage where I feel less inclined to spend much more money on the hobby due to other commitments in life (newly married and just got a house). If i stay with the 600mm, I probably have to wait a much longer time to get the 300mm instead of immediate. This will cause me inconvenience in terms of inability to use that lens on my favorite terns and raptors shooting. Of course, I also realised that half of my photography in a year is done during travels around the region (Asia/Australia). As such, I imagine that 500mm would be much easier to pack and carry for travels. My main body now is the 7D and my aim is to pair a 7D with the super telephoto (500/600mm) and a 1DM4 with the 300mm.
What do you guys think? What would you do in my shoes? I know there has been discussions on 500 vs 600 but I just cannot make up my mind! :lol:

Step down to the 500 f/4 as it will fit as carry on luggage and is no
where as heavy as the 600 f/4 (the 800 f/5.6 apart from being newer is lighter than the 600 f/4)

Then get the 300 f/2.8 for closer work.

I agree with Christopher, in some cases can also HH the 500 and it is lighter/portable. Love your dream team, and you can swap the bodies with the 1.3 sensor on the 500 and the 1.6 on the 300 for better reach combinations. I like your plan and congrats on the marriage and house.

Thanks both! Gave me some confidence that my decision won't go wrong! Thanks Jeff for the well wishes.:)