I have encountered a small problem in Lightroom 4.1 RC. In preferences there is an option to send images to Photoshop as 8-bit images. Sometimes I prefer to do this. I understand the ramifications. If I change the option in the preferences, close the options, and then reopen them the main external editor options still indicate 16-bit. If I have a tiff image in Lightroom that I have converted to 8-bit in Photoshop, and I decide to send that tiff image to Photoshop, Lightroom will send it as a 16-bit image. At least that is what Photoshop indicates. You can change the option in the Lightroom preferences, but it will not stick.
I'm not looking for any workarounds. It's just a little feature that doesn't seem to be working properly.
I'm probably not a good one to answer that question for you. I'm using a 32-bit Windows 7 computer, 4 GB RAM, dual core. The 4.1 RC is probably a little more sluggish on my computer than Lightroom 3.6. But it's tolerable, in my opinion. I have done most of my experimenting with some scanned images, and the Clarity adjustment really makes a difference in some of those scanned images. All in all, I think Lightroom 4 will be pretty good. But I think Adobe probably released it a little prematurely. It still has some flaws. I'm waiting for the 4.1 official release to decide, but I probably will purchase Lightroom 4.