One difference between the dev and std editions is the wifi chipset - 6235 in std, 6230 in dev (and some reports of the AR9462 in others). The wifi was practically unusable for me until I manually disabled power-saving on the wifi interface.
Also had a couple of instances where the machine has dropped into a coma (even on full battery). Usually after rebooting or suspending. Quite scary when it happens, since the long-hold power button trick doesn't always revive it. It usually comes back to life later but I wish I knew what was causing this.
Also have to run the battery all the way down to 0% (the point at which the HW forces a shutdown) and charge back up to 100% every couple of months else the calibration goes wonky.
Lovely machine though.
So you don't have to obtain the Dell drivers separately? They are included in ubuntu 12 onward?