Yes, that beam and dual rails is a winning combo and it's still the core of my build.
Ascalon has been through some changes since the first post. I've replaced the multicannons with a couple of efficient gimballed beams - while it misses out on the corrosive shell special effect, dogfighting small ships is no longer a struggle. I'm thinking of engineering them into healing beams as they've proven very effective in wings.
The other change is that the rails now use sturdy mount for the heat reduction instead of increased ammo capacity. One of the rails is a super-penetrator to damage modules, but the other has feedback cascade to deal with those Cutters/Anacondas sporting neverending shield cell banks.