[Suicide Junkie]

I would reccommend starting at 30%/30%/30% (10% miscellaneous devices)
Do a bunch of simulations with varying amounts of each, and see what a good balance is for your tech level.

Once you meet some aliens, try to have +1 speed over thier ships. When ship speeds get too high, switch back to the slow, heavy ships which can swat the flies.
A mix would be good: fast interceptors, and heavy assault ships.