"It's top speed was 421MPH! "
That's rather slow for a fighter that was only entering service in mid 1945. The P-51H which was entering service with the USAAF at the same time had a top speed in the range of 485 MPH; the P-47M which had entered service 6 months earlier (and saw combat) could do around 475. The F8F's main performance attribute was climbing ability, not speed. Remember this plane was concieved as a lightweight interceptor rather than as a general-purpose fighter which the USN already had plenty of.
G-suits had been in use for over a year by the time the F8F came into use. The F8F was not the most maneuverable fighter in the USN inventory--that honor falls to the lowly FM2 Wildcat, which was rated by the USN as their best dogfignter for under 10,000 feet beating even the F8F in this regard. Nor was it the fastest; the F4U-4 was about 25 MPH faster at combat altitudes. However, the F8F could take off and reach CAP altitude faster than anything else the USN had at the time.
The F8F was basically intended to be a Kamikaze killer, something which the USN desperately needed as Kamikazes had the potential to cripple our carrier fleet (in spring 1945 they knocked several of our big carriers out of action, a feat which the Japanese had been incapable of since 1942). Even with the excellent F8F, it's likely that our carrier fleet would have suffered signigant damage in an invasion of Japan as the Japanese had thousands of Kamikaze planes ready. Okinawa would have looked like a picnic.
J_A_B
