small vs large ships

My impression so far is that small ships are not worth it.
I designed a thrust-8 class-4 beam-armed (FS,AS) ship at mass 
50, points 162 and flew three of them with another ship vs 
2 BC-BB sized ships.  The enemy had level-2 screens which made 
the class-4 fairly impotent.  They concentrated on the larger 
ship (they didn't like the 8 pulse torpedoes) because the trio 
weren't that effective.  I had designed a mass 100 ship with 
2 class-4s and it had a couple of defense systems also (class-1s
or PDS).  I think I like the larger ship over 2 smaller
ones, or in the example a mass 150 ship instead of the three.

Glen