The P-51D wins out overall in speed; more speed with less horsepower (1720 vs 2000-2050 for the Spit and Tempest). It had a very fast airframe.
The Tempest is clearly the fastest below 15,000 ft, but the Sabre sucked above that because of its very simple supercharging.
The Spitfire climbs like a lift. Its climbing harder at 15,000 feet than the others are at 5,000 feet. Sometimes there is no substitute for the small airframe, powerful motor, big wing combination. Fastest at high alt, but only by a squeak.
Well, I am not surprised that the P-47 M is far superior to the P-51 but I am surprised that as low as 15,000ft, the P-47 D is about on par with the P-51 in climb and at the margin at which it exceeds the P-51 at 28,000ft.
Are those P-51 figures at WEP and combat weight (full internal fuel and ammunition)?
How about the P-47-N. If you reduced the internal fuel load to that of the P-47-M or P-47-D, I wonder how she would climb? I understand that the P-47-N had fuel cells and not tanks and that they didn't need to be kept full or even used at all. Normally, you get condensation in tanks from the unused, air filled volume.
The P-47 D and M models had an internal fuel capacity of 370 gallons. The N had an internal fuel capacity of 570 gallons. At about 6.5lbs per gallon, that would be 1,300 pounds. The P-47 N had a combat weight of 16,300lbs so the weight would drop to 15,000 lbs.
P-47 D - 14,500lbs
P-47 M - 13,275lbs
P-47 N - 15,000lbs
It would still weigh 500lbs more than a D but would have the benefit of larger wing area and the horsepower of the M.
Frankly, I don't think that at 5,000 ft, she would be able to climb much more than about 3,350fpm or so.
At combat load (16,300lbs), she climbed 2,950fpm at 5,000ft. Still, I might add, impressive for a single engined airplane weighing more than 8 tons. In fact, even at combat weight, she could climb at 1,600fpm vs. the P-51D at 1,030fpm at an altitude of 28,000ft.