the past 6+ months has been more about stability and replacing flaky Nokia bits where possible.
Want to see something you'll never see with PR 1.2 or 1.3? Check out the picture below, which I snapped earlier today. Note the up time, 3 week of solid running, and it's still doing well.
But I do think, if you're having any issues at all, CSSU will likely fix a whole lot more than it breaks. To date, I haven't found anything that CSSU breaks, but I'm sure it breaks something somewhere, as that's the nature of change.