Yep, the Solo is just like a PerformanceBox and the Solo DL is like a PBox + sensor bridge + analog sensors but at anmuch lower price and using the built in sensors from the ECU. My original setup is documented here:
Which produce videos like this one:
Which were useful, but not as compelling to learn from without steering, throttle and brake info. RPM, oil temp, water temp, IATs were just sugar on top. The issue was the cost of getting the data was expensive and the only one that had good ECU integration was AiM.
Final point - you can't actually get a Solo DL yet in the states. It probably won't be available until October or so while the system is vetted in other markets. I picked mine up for $700 AUD when I was in Australia for work two weeks ago. I think pricing in the US will be $800, but don't want to misrepresent that, so wait for the official bimmer world pricing. I would re-buy it in a heartbeat at that price and with just what it currently has in terms of functionality. Cheaper and more functional than any other unit that can do what this does.