Thanks for the tips/replies -- especially unplugging which I haven't been doing
although that might not be my problem (see below).
As for how hard it is to change, like I said before it's more of an inconvenience than anything -- although the battery is housed behind a panel on the back with like 6-8 screws, not just two.
Also, I realized that I do have passive EMG's -- H4's to be exact -- but the afterburner (push/pull knob adding boost/distortion) is what is battery operated, so I'm not sure if unplugging helps this or not. I've usually been playing with the afterburner on and then when I'm done just leaving the knob pulled out, so I'll try making sure it's off.
Finally, the real problem is probably just a cheap battery -- it was an off-brand that must have come straight from the factory, so we'll see how long the new one lasts.
I wouldn't trade in a guitar just because I had to remove a few screws -- but that on top of the fact that the tremolo is crap (IMHO) on top of the fact that the neck doesn't feel/play quite "right" the way I like, etc. makes me think about getting something else. Oh well -- lesson learned and as far as new guitars go I didn't spend a ton on this one. I'm -MUCH- happier with my RG1527 and have been playing it almost exclusively -- which is why when I did pick up the ESP and it was acting flakey it got me wondering.