Well, I finally received the ONITE battery I ordered a while back (I am overseas, so had to wait for someone visiting the States to return it for me), and so far after one day of use it's certainly an improvement over my old Nokia-branded batteries. Of course, we'll have to see how it holds up over time, but this is what I can report at the moment...

The seller seems very responsive -- they contacted me a couple of times to find out if there was any trouble and to request that I submit a review on Amazon -- make of that what you will, but it probably means that if there were any problems then they would do their best to solve it...