TR,
Unfortunately Spitfire did not have the legs of the Packard Merlin powered P51D Mustang so fighter sweeps into Germany would have been difficult before the invasion. The change from 8 machine guns to a mixture of cannons and machine guns was a big step forward. the initial introduction of the FW 190A spurred the development of the Mk9, probably the greatest variant as the Mk 5 had to have clipped wings and cropped superchargers to try to maintain some parity. All in all I believe that the Spitfire was the finest fighter of its generation, but there again I'm biased.
Mosquito's did have the equivalent bomb load of the B17 and the range, just it did not have the capacity to go up to the bomb load on a Lancaster with 12,000 and 22,000lb Tallboy and Grand Slam respectively. The main problem with the Mosquito was it could could not really be deployed in places of heat humidity and believe it or not termites, the Beaufighter served in these places. The speed and agility and as precision low level bomber was unmatched in WW2 and the Luftwaffe even produced a version of the FW 190 in the form of the FW TA152 to try to combat the Mosquito, albeit unsuccessfully. Goering was forever raging about the Mosquito ability to reach Berlin and drop bombs.
For longer range maritime operations, the Sunderland and Liberator came into their own, as the Mosquito could carry out anti-shipping strikes using the Teste modification, but the main aircraft was the Beaufighter and the Beaufort.
All combat aircraft have good and bad points, the Mosquito had range speed and operational height but was a very difficult to land with only one engine and many crew were killed, but when you consider it was a fighter, night fighter, precision bomber, area bomber, pathfinder and anti-shipping strike, then it was a damn fine aircraft, sort of a Tornado F3/GR1/4 today. Combat aircraft is a case of horses for courses and in the words of General Le May 'you can only go to war with what you have on the day.'
Looks as if we are all of the same thoughts up to now, unusual on here.