The Me-262 out classed everything and might have made an impact in the bombing campaign, except that an increasingly paranoid Hitler insisted that it be used against ground troops. Adolf Galland, in his book
The First and The Last recounts the jubilation when a Me-262 first shot down a DeHaveland "Mosquito". Until then nothing could touch it.
Regarding the relative size of the WWII heavy bombers, the Douglas A1E (Nee AD; designed during the war but did not become operational until after.) could carry the load of a B-17 and with only a single engine. It could also fly as far as a B-17, though with a lesser ordinance load. In the mid 1960's I saw these plane deck launching (not using catapults) off USS Hancock with two 1000# bombs, eight 200# bombs two rocket pods, four 20mm guns, and an external fuel tank. Actually the medium bombers of WWII could carry the same load as the heavies, just not as far.
Relating to the size of modern war planes; the A-4 Skyhawk was specifically designed to provide a smaller, jet powered, bomber for the older Essex class carriers. While the catapults and arresting gear could handle anything, the lack of deck and hanger space limited them to A-1E's, A-4's and F-8's. A detachment of A-3D's was assigned but usually operated from a shore base.