At the time I bought my quartz version, I did get a chance to view it at the Cartier Tank event at Knightsbridge.
There's a lot of hype on it, but in the end I didn't want to be beholden to Cartier when it came to servicing. The SolarBeat tech is new, and while the rated servicing interval is 15 years (if I don't remember wrong), warranty remains at 8 years. It is likely proprietary and nobody really has any info on useful details like the reserve, or how the movement actually works, not even the boutique I went to.
In the end, since the battery life of the quartz model is touted to be 8 years.. Quartz it is.
Another consideration is that there is a slight difference (very slight, but if you look closely it's there) in that the numerals are slightly sunken in, due to the need for slits to let the light reach the solar panel. It was also out of stock everywhere, with no indication on the expected wait time... So on balance, I went with quartz.
No regrets as I feel while SolarBeat tech is new to Cartier and the implementation in the Tank is cool, but it is by no means a new technology or anything to be wowed by, objectively speaking. Sometimes just need to cut through the hype to decide what you really want from the watch.
