I've found unity is a bit heavy for my poor little netbook, and have found xfce a bit better for performance.
I use Linux mint (which is based on Ubuntu) for my main dev machine. The only limitation I've had with it is video- it can't handle the goPro stuff very well.
I've been using every LTS release since the first ever, and I can't praise it enough. Keep up the good work!
I think it's a decent browser, it's only drawback is it's single-threaded.
IIRC Firefox is doing decently with scrolling on OS X with Apple's trackpads, but it doesn't work as well with the same trackpad in elementaryOS (or with the touchscreen in Windows). Midori works perfectly.
From my experience, scrolling well is a bigger deal than how many threads it has for whether or not I like using a browser. I know there are stability advantages to the process separation, but I haven't had any trouble.