Interestingly, Dr. Leachman works for Apple computer in Canada, could there be some distaste for CEREC because it uses microsoft os? You may be a dentist/scientist but are you also a salesman of sorts? Besides, why bash Hyundai's? Have you ever driven one? Maybe you haven't driven a CEREC either, or have you? I'll objectively as possible give my input...
I have been using CEREC for 7 years and have made thousands of restorations with it- it works very well and I have had very few failures...most of the few were due to operator error in the first year. It cannot be used for everything. It is not perfect, it is expensive, it was the only game in town until fairy recently. It is fast, reliable and is supported well. I know one of the engineers who worked developing E4D and it is not a perfect system either. Why don't you mention some of your frustrations/challenges with it? Anytime someone comes with derogatory comments first...think about why. I am pleased that Sirona has competition so we all win in the long term( especially lower prices would be nice). It would be great to have a completely unbiased viewpoint but no one is going to give it because we all have some bias.
Titanium dioxide powder is the white writing on m&m candy, it is a coating lightly sprayed, it is easy to do and master without being a big deal. It is not plastered on. Concerns over powder covering the margins? No milling machine can make a flush joint as there is always a small space between the margin and the restoration. Does E4D really have a more "closed" margin, maybe or maybe not. Cement fills in this minute clinically insignificant space.
Do your homework, ask users of both systems, check with relatively unbiased sources where possible...