Are some techs/wepons useless?

[Suicide Junkie]

Why not mod, and have the techs go:

- Shield I
- PS I, & SR I
- Shield II
- PS II, & SR II
- Shield III
- PS III, & SR III
etc.

You can add the requirement that phased shields need an equivalent phased energy level, and you'll still get something at each shield tech level.
Plus, the increase in shield strength won't be so steep.
I would also recommend making phased shields equal or slightly weaker than normal shields, since they protect against more weapons.