I don't know enough about Ram & sharing to know what the difference is here.
Normally, I run Chrome in one desktop for personal use, and Firefox on a second desktop for business. I like the separation of saved passwords and whatnot.
However, I recently learned that I can open two different profiles in Firefox at the same time, so I was wondering if that would be cheaper to my system resources, or not? Out the door, I don't think it would save more than 40-60mb of ram... but I'm wondering, 3 hours later, if ram handling will be better using just one browser for all my heavy lifting.
I only have 2gb of ram and I run iTunes and Photoshop as well, almost all day. So I like to save ram where I can.
UPDATE: I've been centering around chrome more recently and using firefox for testing. Dev isn't bad on Chrome and it's great at releasing memory when I close tabs. In retrospect, I think the best answer to this question is simply for me to buy another 2gb of ram.