I really like Hera and much better episode overall...although I do find it funny that they couldn't seem to figure out to simply go around the Imperial blockade...consisting of a whopping 4 ships.
Also, I guess the new canon is now that the B-wing was single-handedly designed in a garage by a pygmy Mon Calamari and sports a super-duper Death Star laser mode. *sigh* I guess since they're going with the notion of there being multiple Rebel cells (despite it being clearly stated that Yavin 4 is THE rebel base and it's destruction would be the end of the Rebellion), Dodonna is just a moron for not adopting a fighter as ridiculously powerful as the B-wing instead of those lame X-wings and Y-wings. By ANH, he's had 5 years to do so.
It was never stated that the base on Yavin IV was THE Rebel base, if so, where was the fleet that we saw in Empire and Jedi, where was Mon Mothma? It was almost certainly A Rebel base, or maybe one pretending to be THE base, or was the only one that the Empire knew for certain existed. At any rate, rebellion 101 states that you don't put all your eggs in one basket, you set up a cell system and no cell knows anything about where another cell is or anything about its members, this way, if one cell is compromised or its members captured, they can't reveal anything about the other cells. You also don't won't to put your entire organization in one location that would allow an enemy with vastly greater resources, manpower, and firepower to take out and thus completely wipe out your rebellion with one fell stroke.
As for the firepower of the B-Wing, it's super gun wasn't all that powerful and it seemed to be pretty energy intensive to use too. Remember, they weren't going against Star Destroyers, they were only taking light cruisers, cruisers so small that they only had a few turbolaser mounts and couldn't even carry its own TIE complement, and the other light cruiser accompanying it could only carry a few TIEs on the outside of its hull. Even then, it's not like the B-Wing took out the one cruiser with just one shot, it took two strafing shots along its hull to take it out and even then it wasn't instantaneous. So, while it's a potent anti-capital ship fighter, it probably wouldn't be that effective against something as large and heavily armed and shielded as a Star Destroyer. And as MJF has mentioned, it's most likely not a good dogfighter, a TIE fighter would probably run circles around it meaning that it would still require A & X-Wings as escorts.