Why buy this one over that one? I can't say. Is it or any other fully electronic CCR in the $8-$10,000 price range considerably better than the other one? Has there been any breakthroughs in technology that are missing out? It all boils down to personal preference... yes?
At this point in the game... what other features are people expecting on sport rebreathers? I know people want CO2 monitoring, but with the sentinel being over $13,000 is that something that should be added to a unit that apparently set the target price point under $10k??
IMO, there were notable features like the Peter Reedy influence with the counterlung water drain, water traps, and DSV which is similar to the Topaz. I also found the easy to hear solenoid nice. One thing I didn't mention in the article is the ability to add a fourth O2 sensor and monitoring for it if desired.
I guess (also IMO) the other key feature is that this product is coming from a major manufacturer in the dive industry with a long standing reputation for producing quality products, which this rebreather definitely is... a quality product.