Process-per-tab is supposed to cut down on single tabs taking down the whole browser, but in Chrome's case it just means that Flash will crash daily requiring you to reboot/reload tabs you didn't even know were running Flash. That is, process-per-tab falls down a bit when the thing that crashes is running in multiple tabs anyway.
That may be the case, and to be sure I switched to Chrome in the first place due to the lag in having an 800M Firefox process stinking up the joint, so for now my conclusion is that they both suck in subtly different ways, behave identically 80% of the time, and the remainder I'll just bat back and forth with my default browser setting.