Are any of you guys urban explorers? What kind of gear do you use?

I've recently gotten into something called urban exploring, which is kind of like
cave diving, except in the city. You go into storm overflows, old aqueducts, abandoned subway tunnels, etc, or try to get into old abandoned buildings like out of use state psych hospitals, or into the nether regions of in use buildings. Anyways, the hobby requires extensive use of flashlights and I've been finding myself more and more occupied with selecting lights instead of planning trips. I was very pleasantly surprised to find an entire community of "flashaholics." My question to you guys is, if you were gonna do something like what I described above, what would you use? This is my current setup. For underground trips, I use a Princeton Tec Apex headlamp with an Inova X1 as my backup. I used to use an Arc AAA-P for my backup (which seems to be very popular here), but i didn't like carrying two kinds of batteries. For above ground, i use a PT Tec 40 with the stock bulb swapped out with an EverLED and the X1 again for backup. This has worked well for me. Critiques? suggestions?

Just me, but I would carry enough batts so that I could have 24 hours of light.
Consider a photon type light that strobes in case you get stuck or hurt and can be found.
I would say carry one other light incase one gets dropped or lost.
Do a search for caving threads to see what others have done/used.

Here's a couple of previous threads already started around these halls...we'll close this one so we can continue in one or both of them. Thanks...

Here's one... & ...and here's another.

You may be able to find more using the various search features that are available, but these were two larger ones that appeared in my results.