Pinnacle of Piston fighter: XP-72 vs Spiteful Mk XVI? (5 Viewers)

[mig-31bm]

Due to the jet age, various super props never go to production despite their high performance. Among those, it can be said that XP-72 and Spiteful F.16 were the most high capable design.
So let say if these prototype got to production stage, which would be the ultimate piston fighter?
XP-72

Performance of the XP-72 .
Sea level speed: 405mph (651 km/h)
Top speed: 490mph (788.5 km/h) at 25,000 feet
3.5 minutes to 15000 feet

Engine horsepower: R4360 engine
3450hp at SL
3000hp at 25000 feet
Normal take off weight: 14,760 lb (6,695 kg)
Wing area: 27.9 m2
Wing loading: 239.9 kg/m2
Power to weight: 0.515 hp/kg (0.233 hp/lbs)
Weapons:
Six 0.50 caliber machine gun

Spiteful Mk XVI (also known as Spiteful F.16)

Performance of Spiteful XVI (F.16)
Top speed: 494 mph (795 km/h) at 27,800 ft (8,473 m).
There is no information about low level top speed of Spiteful Mk XVI (F.16) however, Spiteful Mk.XIV (F.14) with pretty much same aerodynamic and a weaker 2,375 hp (1,771 kW) Rolls-Royce Griffon 69 could achieve: 409 mph (658 km/h) at sea level, 437 mph (703 km/h) at 5,500 ft (1,676 m) and and 483 mph (777 km/h) at 21,000 ft (6,401 m)
Engine horse power:
Spiteful number RB518 was fitted with a 2,420 hp (1,805 kW) Griffon 101 engine to become the sole Spiteful F.XVI (F.16). The Griffon 101 had a two-stage, three-speed supercharger and turned a five-blade, single rotation propeller.
Normal take off weight: 4513 kg
Wing area: 20 m2
Wing loading: 225.65 kg/m2
Power to weight: 0.536 hp/kg (0.24 hp/lbs)
Weapons:
Four 20 mm cannon.

Compare with some mass produced super props.
P-51H

Performance of the P-51H
Sea level speed: 413 mph ( 664.6 km/h)
Top speed: 474 mph (762.8 km/h) at 22,700 ft
Engine horsepower:
Merlin V-1650-9 engine with 2218 HP at WEP
Normal take off weight: 9450 lbs (4286 kg)
Wing area: 21.6 m2 (233.3 ft2)
Wing loading: 198.4 kg/m2
Power to weight: 0.517 hp/kg (0.234 hp/lbs)
Weapons:
Six 0.50 caliber machine gun

F4U-5

Performance of the F4U-5
Sea level speed: 347 knots = 399 mph (642 km/h)
Top speed: 408 knots = 469.5 mph (755.6 km/h) at 27,000 ft
Engine horsepower:
R-2800-32W engine with 2760 HP at WEP
Normal take off weight: 12,901 lbs (5851.79 kg)
Wing area: 29.172 m2 ( 314 ft2)
Wing loading: 200.5 kg/m2
Power to weight: 0.47 hp/kg ( 0.213 hp/lbs)
Weapons:
Four 20 mm cannon

 

[PAT303]

The XP-72 was never a fighter unlike the other three.

 

[mig-31bm]

The XP-72 was never a fighter unlike the other three.

As I understand it, XP-72 was a prototype exactly same as Spiteful Mk XVI. There are two prototype made. The only different was that XP-72 prototype wasn't run at full potential (from what I have heard, they didn't turn on the supercharger while they tested its top speed?). Allegedly, with super charger turned on, XP-72 could have reached something like 540 mph which make it faster than early jet such as Meteor. Ofcourse, that is only an estimate and production version could be a lot slower, for example: XP-51G could reach 492 mph, however, production P-51H is limited to 474 mph