I bought a Millenium performance, which is mostly nice. Using the King engine, it's customizable. All those personalities, as probably just a set of parameters. While the King performance lacks the personalities, it does have the personalities. It also has a lot of levels, and you can adjust the clock speed as well I think. Including adaptive levels. So someone can probably find a way to get a game that's challenging, but not impossible.
Because of a good black Friday deal, I ordered the fancier, sensor board version called the Chess Classics Exclusive. MSRP is USD $750, which I would find too expensive, had I not got it for 200 off or something like that.
The downside of the Exclusive, is that you have a separate computer module, making it less portable. The King performance is a single board with built in computer...but no internal battery, so you need to buy their power pack or find something similar.
I did have some quality issues with the performance, such as some peeling veneer, and the brass plate seeming to not be glued down perfectly.
The exclusive, besides the disadadvantage of a separate computer, has the following advantages:
* Pieces might be slightly nicer on the Exclusive? Not 100% sure
* Sensor board with piece recgonition...this seems very responsive, I am pleased with this upgrade
* Two chess engines, The King and the Chess Genius, which people might enjoy the variety ( I think they have different opening books as well)
* Display is bigger, which is a good thing when you are 57 like me.
I know some people have wondered WHY you would not just use a smartphone with a sensor board, and why you would want an embedded computer? IMO, technology changes, maybe one day a newer phone simply won't support the board. Having been burned before, I like the idea of a chessboard WITH computer of it's own. Personal preference.
As for why not just use a computer or phone and no board, well, if you don't like a physical board, these products are not aimed at you
I envied my classmate who was gifted a Mephisto Mondial for his birthday. Since then I never lost interest in dedicated chess computers.