I have no problems whatsoever with the Centaur. I like the modern design and thinness of the board. The circlular leds previously seen on the IOS Stockfish app are a welcome appearance to the design of a chess computer (I actually like the the way a Lexibook highlights its moves with central LEDs).
If you disgard the first two playing modes of yhe Centaur and just use the Expert level, Stockfish has given me hours of enjoyment being beaten by this powerful engine.
In my early days of chess computer collecting many years ago now, I would pray that the next chesscomputer I would buy would actually have some end game knowledge but being an atheist my prayers where never answered.
I don't need to be able to upgrade my Centaur because it is what it is and a lovely designed modern plastic chess computer.
I would just like to add something to think about in general. We all know who programmed all our chess computers and have all the technical data about each model. But spare a thought about who actually designed these machines. Who sat down at a drawing board and initially drew up the designs of the boards that we all admire and collect today. These are the unsung heroes of computer chess for me and we will never probable know who they were.