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Tank made it plain that he regarded the Jumo-powered FW-190D-9 as an "interim solution", leading Luftwaffe pilots to believe that they were going to get an indifferent and clumsy lashup. Once they got their hands on the machine, they found out that the "Dora-Nine", as they called it, was a superb aircraft. It was faster, climbed more rapidly, and handled better than an Anton, and almost certainly the best piston fighter to be fielded in numbers by the Luftwaffe. The Dora-Nine proved to be a nasty handful for American P-51Ds and late-mark RAF Spitfires. Tank was just being fussy.
The Dora-Nine was produced in good numbers, but unfortunately for the Luftwaffe, conditions were becoming increasingly difficult at this late date, with fuel and pilots running desperately short. Many of the FW-190D-9s built never saw combat, and in any case they were too few to have any influence on the course of the war. Those that did see action were often used as "top cover" for airfields operating the Messerschmitt Me-262 jet fighter, whose poor acceleration made it highly vulnerable during landings.
http://www.faqs.org/docs/air/avfw190.html