Yes, but so far as I know, there was no Sherman Jumbo Firefly produced.Well the Brits fitted Shermans with 17-pdrs for a while but the urgency died after the Americans shifted towards M4(76) and phased out M10 production.
The Sherman was a generalist vehicle. The impression I have is that the Jumbo sacrificed general performance towards specific aims. Another 12 tons of armor strained the suspension and sacrificed the Sherman's vaunted mobility. Reliability probably suffered too but with only 300 some built I cant say for sure. AFAIK this tank was to serve two roles:
1) Put it at the head of a column so that it's more likely to survive nasty surprises.
2) Lob shells at concrete fortifications head on
In the second role you'd probably prefer the 75 mm over the 76 mm because you want big boom, not tank armor penetration. In the first role you probably want the 75mm and if you dont the tanks behind you have the 76 mm.
I would say that the Jumbo couldn't out Panther the Panther on account of the insufficient suspension but there were a handful of HVSS Jumbos that wouldn't have had that problem. There were also a minority of Jumbo's refitted with 76mm late in the war. These refits seem to have cropped up mostly in a few gung-ho organizations in France. So if we are talking about 100 tanks out of 10,000 each time that means statistically there was probably one M4e2e8(76) somewhere in Germany or France in 1945 or 1946.
And that one M4e2e8(76) would be the best tank of WWII.
The Sherman Jumbo was an effort to make an assault tank out of the Sherman, hence all of the armor. It was also actually originally intended to mount the 76mm gun M1A1, but was only built with the 75mm gun M3 (though the 76mm upgrade was quite common in the field, especially due to the relative ease of mounting it on the Jumbo, since the turret and mantlet were originally designed to accept it).
And so far as I know, the Sherman Jumbo was still more reliable than the Panther (even if it was less reliable than the baseline Sherman), and since its frontal armor was roughly equal and its side armor was better and the gun would add negligible weight, it's my impression that the end result of a hypothetical 17-pdr/KwK42 upgunning of the Jumbo would have the main strengths of the Panther (armor, tank-killing firepower) without its most glaring weakness (terrible reliability). Of course, this is all theorycraft and not actually testable or terribly relevant to the actual discussion at hand.
Also, I doubt that you'd find many A2 Shermans in France, since the US Army had pretty much no interest in the diesel-engined Sherman as it would complicate logistics (everything else the army was using used gasoline) for little gain, so they gave the diesel Shermans to their red-haired stepchild, the Marine Corps and to the Soviets, who were using diesel for pretty much everything else anyway.