Cessna took on the Thielert as a production engine 172TD in 2008, a dozen went to the Iraq Airforce. In the mean time Thielert went broke and the program was abandoned.
As Cessna now have the 182JT-A and have not re released the 172TD it makes you wonder.
Having flown a 172R with the Centurion I can tell you it's a dog.
STC's to fit the 135 hp Centurion engine in the Warrior have been around since around 2005, Thielert would not offer the 155 hp version into the retrofit market trying to keep it up there sleeve to induce the OEMs with more HP.
Gearbox, clutch and fuel pump require frequent replacement. The 2,400 TBO has been promised since around 2005. This was to be paid pro-rata on the 1,000 hour engines but as Thielert went tits up many owners were left high and dry.
Yes common Rail diesels are very reliable and efficient however to get the power to weight small diesels had to be used and pumped up. The base Thielert in its previous Benz spec is only about 60 kW and will do millions of Kms, nearly double the output and boost and the reliability goes out of the window. In the car it cruises at probably less than 30 kW. Diesel has excellent lubricity so the HP fuel pump survives in the automotive world on Jet A1 the pumps just don't last, these things run nearly 20,000 psi of fuel pressure between the HP pump and the rail and the by product is heat, having flown the Simpson with the fuel temp in the red I can tell you this is also a major concern.