right now my family has an x100, om e-m5, fuji x-pro1, panasonic gh2, a s90, and just received a sony rx100. We plan to downsize and sell / pass on several of these cameras. clearly the s90 is going, but which others we will keep and which we will get rid of is a really hard choice. I guess if we could keep just one camera it would be the OM E-M5 because the image quality is decent, with one of the pancake lens it's pretty light / compact, and I appreciate the versatility of the multiple lens, even if 80% of the time I use the 20/1.7 lens.
the x100 fits my me really well. It's my everyday carry camera. I love the ergonomics (though the menu system could be better). if it had the x-pro1 sensor, I could maybe consider this being my only camera... but I prefer better low light performance for a good bit of my non backpacking photography and having other lens lengths is useful... though if I am honest, most likely 90% of my images can be handled by it's lens. So my minimalist leanings would love this to be my only camera, but practically suggests this is one of the camera that will ultimately go.
I *love* the image quality of the x-pro1... but the speed and accuracy of the auto focus, and the pain of using manual focus is a real handicap. Hopefully a firmware upgrade will improve this soon, just as fuji fixed a number of problems with the X100. The other downside is while not not huge, and certainly lighter than many DSLRs, the x-pro1 camera is larger than you might expect. The x100 slips inside my everyday carry bag, the x-pro1 even with the smallest lens doesn't.
The gh2 is better for video and the fully articulated screen is quite useful at times. The e-m5 has 1-2 stop advantage, but at low ISO settings I don't find the e-m5 having significantly better image quality.
the size of the s90 was perfect, but very rarely was I satisfied with image quality. It was what I would take on backpacking trips when I was really trying to keep weight down... but most of the time a heavier camera came on the trip. I am hoping the sony rx100 which be good enough that I won't feel compelled to bring a larger / heavier camera. We will see if that is the case.