I have the dashdyno. I like it since it has user (multi) programmable alarms thru 3 bright LED's. They tell me when a regen takes place. And no, it doesn't simply fit where i have it, there's not much left of the inner bits of the tray. The buttons light up to nearly BMW red at night.
One piece of advice: be sure the OBD reader shuts down upon key off. If it doesn't, it will keep the engine ECU alive for 30 minutes and potentially cause a low battery . You'll know when the stop/start button remains on. I've been there, the dashdyno guys have been great and provided me with a beta version to shut it down on seeing zero rpm, which is now a selectable option