Then you retire, join the "Hooligan Brown Water Navy" AND get a life! There is life after the Guard!!!

IMHO. I'd swap the headlamp for a 2 AA powered light then you only need to carry one set of spare batteries.

And if you do so I find the Nite-Ize headband works well. My mini-mag in my appartment is on one of these headbands permanently. But the Tactikka Plus is attractive to me, for its red lens so that you don't need cellophane and I'm guessing it would fit on a helmet more securely.

Ohhhh, I've come to really enjoy my Princeton Tec EOS headlamp. My handhelds all stay in the house, expect for one - my Fenix P1 CE LED that uses the same CR123A batteries as my Miox - is in my pack as a small, but powerful, backup light.

Another option could be to go with an AAA powered GPS, IIRC I saw a 3 AAA powered last time I was looking through web sites for them.
I'm going to go with an AA powered as everything in my large bob is AA powered, flashlights, radio, scanner, etc. I'm down to AAA's in a radio in my truck bob and my Arc AAA EDC, and a couple AAA powered Mag Lights in the truck bob, all of which are I plan to rotate out to AA models. Primary power is Sanyo Eneloop with Alkaline and some Lithium AA's for back up.

There is a very similiar, DIY item here:
http://www.therangerdigest.com/Tips___Tricks/MULTI-PURPOSE_SAW/body_multi-purpose_saw.html

Haven't built one yet. Not the operative word there is yet, can't find good blades.

Yeah, that is a pain but I really like the Tikka. Ever since I started using headlamps, it's been hard for me to imagine when hands free light wouldn't be advantageous, so I steered away from handhelds. At the time I made the purchase I wasn't aware of a AA LED headlamp in my price range - I guess that's why it pays to do your research.

Matt, I had the rare honour of meeting a USS Indianapolis survivor. We talked at length and he suddenly invited me to his home office. It was obviously the man's inner sanctom with a rich life lived on display. He opened a closet and pulled out a faded MK 1 kapok lifejacket that made the worn out junk we surveyed ( toss out for you civilians)in the 70s look good. It was stencilled USS Indianapolis. He held onto that jacket even after being picked up. He told me bluntly whenever a life crisis came up later in life; a sick daughter, job loss etc. He would privately put his lifejacket on and sit quietly by himself for awhile. Your doing o.k. Don't sweat the small stuff as taught in rule # 1 and remember what rule # 2 is.

do the heatsheet and the bivvy duplicate each other?

Not totally. The heatsheet is just a sheet; the heatsheet bivy is the same stuff as bivy. I carry a hs bivy and a tarp in my ditch kit, one probably will keep you warm, the other will probably keep the wind and rain at bay. You could make a bivy into a sheet, but not the other way around, not with much success; besides, why pay extra for the bivy if you plan on slitting anyway? :P