Yeah, I mentioned that priority was being given to the Jet Development - Aside from that, the He 219 and the Do 335 were the two piston-engined designs that were the main Nightfighter Programs, as regard to progressing past the Do 217 N, the Bf 110 and the Ju 88, although the latter's G series was still in the running...- The He 219's main problems were the Generalluftzeugmeister Erhard Milch, who despised Heinkel and Kammhuber, and wanted to push the Ju 88 G and the Do 335 programs instead. - Also, the availability of the DB 603 G L series engines, which were initially specified for the He 219, were well behind delivery schedule, so earlier models had to make do with the lesser-powered DB 603 A engines. They eventually got the right engines in them, the He 219 A7 becoming the most important service version of the fighter. Albert Speer, Minister for Armaments, got this version rolling, overiding Milch.- By late 1943, I/NJG 1 were the main operators, 7/NJG 5 in Flensburg also having them with their Ju 88's Bf 110's. - They played around with a He 319 419 version, and tried using Jumo 222's on them, but the basic He 219 A series stayed-on and did the work up to War's end.....- IMHO , the He 219 was an outstanding aircraft, suffering few teething troubles that other contemporaries had, vacillation by Technisches Amt, Milch's interference and Allied bombing doing the most damage to it's program....If they'd had more sooner, the dear old Mossie might've had a tough time....but then again, they never got around to trying Griffons on the Mosquito....would've really left 'em behind then.....P.38's too....!!!