Saben,
I agree with your statement:
"Lastly, I agree that balance is important. But in my mind that balance is between missile, beam, boarding, AMS, repair, carriers, troop transports, and special case ships. The effectiveness gain for bothering to research down more than one beam weapon tree is not worth the research expenditure."
That was my point. I did not mean to infer that a player should research more than 1 beam style weapon.
Unless in the full game you would need to reach a certain level in two separate fields to open a new field. EX: MB level 4 and APB level 5 to get "Hull Fracturing Beam of Kluge" field.