I found a Human death ray that I bought off an allied ship that was pretty strong. Approx values below.
1100 native range.
400 hull damage
250 shield damage
7 recharge, whatever accuracy.
So it is not just a racial thing, but that death rays (and megaplasma) have HUGE possible deltas in values. I think thats part of the issue.
If a death ray was 1000 range, 200 shield, 150 hull, 6 sec charge... AND variability was only 50% this would be fine.
Its the variability that makes it tough...and the fact that Celestial ships are loaded to the teeth with death rays...they are literally commonplace. Thats really the issue.