Well, I had good intentions of posting a favorable report of this monitor. I waited until I ran through trying to solve the problem to post the results so I wouldn't post any unfounded guessing.
Turns out the monitor had pretty severe uneven brightness and a pink cast over the brightest part of the monitor. The darkest part of the monitor was approximately the left 1/4 of the monitor. The pink cast was on the other, brighter 3/4, or at least that is where it was most visible. I worked with the calibration at night after work for several days and couldn't clear up the issue. I searched on this forum and others for like problems and found some useful posts about calibrating to the native white point and some other things that I tried to no avail.
I called B and H and they gave me an RGA for the P221. I decided to go ahead and pony up for the PA241 to replace it. I got it in yesterday and hooked it up last night. It has even brightness and no pink cast. As an experiment, I calibrated the PA241 using the puck that came with the P221, as I hadn't returned the P221 yet, to see if it gave the PA241 a pink cast. It didn't. It calibrated the PA241 nicely. The PA241 is a beautiful monitor. I also set it up for 10 bit color and downloaded the ATI test image and verified that it is working. Not sure what that will do for me in the real world, but I will find out as I work with it.
I will attempt to answer your question about the P221. It also is a nice display. It has very deep blacks, maybe more so than the PA241. I had no issue with the size/resolution of the monitor. If I had not had the problem with it, I would have been happy with it. I would point out that this is my first professional level display, so my baseline before these two monitors was from some pretty crappy monitors. I think my issue is an isolated issue with one unit as I have seen many people post positive things about this monitor. It happens. It was resolved in a very customer friendly way.
However, after getting the PA241, I think it is well worth the difference in price. I have spent very little time with the MultiProfiler, but it looks like a great tool as well.
Also, B and H gets major cudos for their customer service.