A few thoughts

1 Medical kit
Fewer variety of bandages and more Kling. Kling wrap can be cravat, tournequit, face mask, joint tape. Oh yeah - bandage. Add imodium or other anti-diaherial since that can become severely dehydrating and incapacitating and is likely in a situation of questionable drinking water.

2 Signalling
Go ahead and take the 1 day ham lisencing course for rought $50.00 from your local ham club and get a decent 2 meter or better yet a tri-band ham hand held. It will weigh about the same as your gmrs radio and will also provide scanning for the emergency services freq's and communications with the emergency communications folks directly - heck, who knows you might even want to participate in emergency communications yourself. I wouldn't bother with the strobe, in it's place you might want to get a PLB but that is probably useless in an urban environment. BTW your mini Grundig SW reciever may be able to get the emergency freq's in your area - check it out.

3 Emergency Devices Group
Do lighten up the flashlight. Led converted miniMag light seems to be a reasonably priced and good option and you can keep the original bulb on hand if you need to throw a more directed beam. Add a cell phone and make sure that you have battery conversions for you HandHeld radios and cell phone to use AA or AAA - which ever you settle on for your flash light. Replace mil-spec candle with NuWick candle

4 Shelter
Add an 8X10 sil-tarp. Beats the garbage bags by a long shot and only weighs 10 oz and takes up almost no room. I second the idea of swim goggles and dust mask. These are cheap and will be helpful in any situation that raises dust or smoke. Not a response to bio-chem attack but if there is explosion, fire or building collapse from earthquake then the dust can become a choking problem or debris in the eyes a sever problem. Also add a good pair of work gloves.

5 Food and water
Depending upon resupply, I would forgo all food except a roll of lifesavers or equivalent and a slim-jim jerky snack (see below comments) Water should be sufficient to get you through 1 day. The container for the first day should be adequate for refill for subsequent days. I would also add a small filter of some kind. There are decent filters built into bottles or as straws or even better small hand powered ceramic ones from katadyn. Don't bother with the MRE heaters, they are pure luxury and a small tommy-cooker combined with a sierra cup will weigh less in the long run work longer and allow for boiling drinking water for purification.

6 Batteries
re-arrange you electronics so that everything except the photon takes either AA or AAA bateries, carry enough lithium rechargable AA's or AAA's to replace all batteries in the device that takes the most (eg the Ham HT which takes 4 AA's) and carry a solar / hand-cranked recharger capable of charging all batteries not in use at once (in this example that is only 4 AA's) This arrangement will be lighter and more long-lasting than what you are currently carrying. Potentially smaller in bulk as well since the extra batteries will be carried in the charger.

7 Miscellaneous gear
Add monocular or binocular or scope. Drop all small cable ties in preference for larger. they don't take up that much more room and long ones can tie up small things while small ones cannot tie up large things. Same goes for the extra zip-locks and garbage bags.

8 Personal effects
Add list of immunizations currently effective and

9 Personal supplies group
You might want a Little John Shovel with some refills, ear-plugs, eye-shades - you may find yourself trying to sleep in a shelter with 500+ of your closest friends replace deoderant with gelled alcohal hand sanitizer (which will burn just as well as sterno for cooking on) Add sunglasses / perscription sunglasses.

General comments. There are many scenarios where you would want to evacuate an area with great urgency. In any of them it is not a great thing to be changing clothes or re-packing things or shouldering a behemoth pack while trying to get through a panicking crowd. Building collapse and fire are the most obvious ones but there are probably others (like the bouncers just peppered the brawling bimbos at the edge of the stage - i digress <img src="images/graemlins/blush.gif" alt="" /> ) In each of these having something small - like a belly bag - is about all you would want to grab to go. It should contain enough to get you through if you get nothing else but will necessarily be minimalist. For example, from your list it might contain a garbage bag for shelter, the space blanket, a plastic rain poncho, and the potable aqua for water and a couple of ziplocks as water containers the photon, the goggles and dust mask, a good pair of work gloves, the cell phone, such of the personal effects as are usually in your wallet, the little-john shovel, 2 oz hand sanitizer, a mini-bic, a classical PSK ALA Dougs altoids kit, the leatherman, the ear plugs and eye shades, the storm whistle and the sierra cup. This bellypack should be expected to get you to your truck. If it needs to it can get you out of the city and perhaps you could survive on it for a week or longer if you had to. Your truck could have a razor scooter or bicycle, a set of carhart coveralls and the rest of your gear - and perhaps a bunch more stuff to make life really comfortable. In any scenario where rapid evacuation is necessary you want to move quickly and lightly. There is no food or water in this belly pack but there is a snare, and fishing kit in the altiods kit and a bottle of potable aqua and a ziplock. And you will have your leatherman. I would also advise that you have a cache that is reachable within a days walk in the worst of situations. Say a locker at a train-station or a self-storage facility or under a friends bed, where you could stash replacement items or a few extra MRE's in-case your truck is crushed in the same collapse that forces you to leave your building. This secondary cache should be selected for survivability - single story building - on a hill - external access to your stuff - etc.

So, I have spewed forth - back to lurking