sorry adler for misleading you, I assure you not deliberate
About the prototype thing, I ment is as the germans seemed to be only a few months away(or a little more resources

) from some truly amazing NF, the Do 335, he 219, the me 262, the Ar 234 are the ones I can think of, something the allies could have found difficult to deal with(but, come to think of it, the p-82 could have been
really scary)
the speed is important(isn't it always?) because you can intercept aircraft much quicker, personally making up slightly for the me-262 range deficet(can also climb to altitude faster)
however, like glider said, the final interception still had to be done by eyeball, and the whole visibal thing i brought up was that the bomber crew would see the me-262 far before it saw the bomber. A corkscrewing bomber I've heard is hard to track at night, and considering the bomber could go into manuvers
before the me 262 could see the bomber, well, it would be difficult (hey pilot, see those twin fireballs heading toward us? I think it would be prudent to go into evasive manuvers now

)
as well, throttals only help so much, the me 262 was not know for it's acceleration, and considering the bomber in a corksrew was changing speed, hieght, and direction, it would be hard to keep with the bomber. the me 262 was also not known for its low speed agility
the metor nf was intcepting buzz bombs, very visable, flying near 400mph on a straight and level course, no where near the same as intercepting a bomber (they had to firewall the throtal just to catch the bloody things)
And as far as the Mk 108, I love the weapon myself, it's just that those shots need to hit, and that I'm not sure about wether that could happen (tajectory doesn't help matters, the one glaring fault of the weapon) but for your benifit, I doubt any other weapon would do any better, and the hiting power is a big +.
given these factors, I doubt the me 262, B-2a or not, would have been astondingly effective against heav bombers, but in the end the ability to outrun those pesky misq. (and shoot them down

) was probably in the minds of many pilots worth it wieght in gold