I have one of these that I used pretty extensively in June/July for some cave work. Yes, it is basically as you describe--like a regular Apex, but with an 8xAA remote pack.
I was not really paying close attention to runtime as I was using it with 2500 mAh Energizer NiMHs (standard style, not LSD style) that I recharged each night. But certainly I used it at least 6-7 hours on some days. I think once or twice I had drained the cells enough that regulation dropped out, and it reverted to a dimmer, long-runtime mode (i.e. there was no difference between Maxbright Low and High modes). By the way, the runtimes I am talking about are with using it exclusively on the Maxbright High mode as when I am in a cave, I like as much light as possible.
This is probably clear to you and others, but if not, when you look at the specs on the regular Apex at the PT website (
http://princetontec.com/products/index.php?id=2), they list the runtime for that regular 4xAA version on the Maxbright High mode as 72 hours. As you are probably aware, you do not actually get 72 hours of regulated, high output use, not on the regular 4xAA version, nor the 8xAA Extreme version!!! You get several hours of regulated, high output use, and then the system kicks back to a much dimmer, long-runtime mode for the remainder of the supposed 72 hours (I alluded to this above). Unfortunately, I never stopped to measure this, so I can't tell you how long it takes for it to go out of regulation. Elsewhere I have seen folks mention numbers for the 4xAA version, so possibly you could just double that as the Extreme 8xAA version as it is just basically two 4xAA packs in parallel. Surely somebody will yell about this statement and correct me--please go ahead!
Finally, regarding modding it with P4, I am really anxious to do so, but I have simply not gotten around to it yet. The increased output and runtime would certainly be appreciated, and it simply seems wasteful not to do so!
I saw your other post in the LED flashlight forum comparing your P4-modded PT Apex to your 135 lumen Fenix L2D. By coincidence, I had a L2D Q5 Premium along with me this summer, and as should be obvious, the Apex Extreme even on Maxbright High was simply no comparison for the L2D Q5 on Turbo mode (supposedly ~180 lumens). So, I am quite eager to do a P4 mod on my PT Apex Extreme to see if it can somewhat level the playing field.
Just for reference, any details about the P4 emitter your modding friend used? I am thinking of this one at DX (
http://www.dealextreme.com/details.dx/sku.2026), but if there are better options available, even if more expensive, then all the better.
