Firefly was designed, built and used as a true multi role aircraft, which has both advantages and disadvantagers as a concept. As a generalization it can be said the Firefly could do a lot of things, but i doubt it could be singled out as doing one thing better than a purpose designed aircraft.....
That said, there are a few things in TPs submission that require clarification. I dont know a lot about the helldiver, so i will leave that part up top the US guys here to clarify on that. But I do have some knowledge on the Firefly, and a few things raised in TPs submission are not the same as my understanding of the aircraft.
Firefly was designed to specification N5/40, which in summary was a spec for a multi-role strike fighter also capable of effective recon and surface strike. It was required to have low landing and stall speeds, so as to be able to escort the 100 knot aircraft then in service with the FAA. It had to possess significant all weather capability and be able to attack targets when attacking blind, that is, at night and in poor or overcast conditions. This led to a number of innovations worth noting about the aircraft
It was fitted with patented Youngman Flaps, which were fully recessed and retractable, When exteneded they could greatly increase manouverability of the aircraft, and reduce stall speeds. This in turn greatly increased the accuracy of bombing for the Firefly, which was exploited after the war by the adoption of the type as an ASW platform. Attacking subs requires the a/c to possess extreme bombing accuracy in order to be effective, and the Firefly possessed this in spades, due to its near ability to "hover" and loiter around the target.
Nearly all the day equipped fireflies were equipped with an advanced ASV radar, to allow blind bombing.
Some hundreds of the type were equipped with AI MKX airborne radar for night fighting, and the type remained the RNs principal night fighter for some years after the war.
The type possed a combat endurance of 746 miles whilst fully armed and loaded, with later marks increased to over 1300 miles whilst in this configuration. its maximum speed whilst bombed up was 286 knots. The biggest weakness of the type was in fact its speed with the FR Mk1 only capable of 316 knots. However the types introduced in 1944 with the Griffin engines increased this almost immediately to 380 knot, which was helpful. To get the 1300 mile range the type had to stick to its optimum cruising speed of 220 knots.
Operationally the type had some success as the following excerpts show. As can be seen from the accounts I have provided, the type showed no great weakness to AA. I dont know that such a claim can be made for the Helldiver.....
"Interestingly, on all points save speed, a Firefly I sent to the US Navy test center at Patuxent River in 1944 more than held its own in air combat against the standard U.S. Navy carrier fighter, the F6F Hellcat - those Youngman flaps worked.
1770 Squadron formed on Fireflies on October 1, 1943, followed by 1771 Squadron in February 1944. 1770 participated in Operation Mascot, the failed attack against the German battleship "Tirpitz" on July 17, 1944, operating from HMS "Indefatigable." 1771 Squadron, aboard HMS "Implacable," flew strikes in Norwegian waters that October, by which time "Indefatigable" and her Fireflies had moved on to join the British Far Eastern Fleet.
From January 1-7, 1945, 1770 Squadron's Fireflies flew rocket strikes against the Pangkalan Brandon refinery on Sumatra, during which Lieutenant D. Levitt shot down a Ki.43 Hayabusa while Sub Lieutenants Redding and Stot shared another in air combat on January 4. 1770 scored two more Ki.43s on January 24, during strikes on the Palembang refineries at Pladjoe and Songei Gerong that required the aircraft to attack through balloon barrages and heavy AAA fire. On January 29, the Fireflies added three more Ki-43s to their score before departing Southeast Asia for service with Task Force 57, the British Pacific Fleet, during the coming invasion of Okinawa.
Five days before D-Day, TF 57 launched strikes on Miyako-jima, southwest of Okinawa, following up during the next 25 days with 13 days of strikes against Japanese forces on Okinawa and Taiwan, with the Fireflies participating in all these actions.
When the BPF retired to Sydney for replenishment in late May, they were joined by HMS "Implacable" and the Fireflies of 1771 Squadron. After strikes against Truk, 1771's Fireflies gained the distinction of being the first British aircraft to fly over Japan on July 10, 1945; on July 24, Fireflies from 1771 and 1772 Squadrons - the latter having relieved 1770 aboard "Indefatigable" - became the first British aircraft over Tokyo. By VJ-Day, another Firefly squadron - 1790 - was operating with the BPF in the night fighter role. A year of successful combat had only begun to show what the airplane was capable of...."