Jesters have less than half of the dps/mass of t1 cybran bombers. I barely see jesters used compared to most other units, and when I do seem them used, they usually don't seem worth-it compared to their mass-equivalent alternatives.
Jester: 170 mass, 50 dps -> ~0.29 dps/mass
T1 cybran bomber: 90 mass, 60 dps -> ~0.67 dps/mass = ~231% jester's dps/mass
T1 cybran ghetto with 6 cybran labs: 330 mass, 126 dps -> 0.38 dps/mass = ~131% jester's dps/mass
T1 aeon ghetto with 6 aeon labs: 372 mass, 162 dps -> ~0.44 dps/mass = ~152% jester's dps/mass
T1 uef ghetto with 6 uef labs: 300 mass, 140 dps -> ~0.47 dps/mass = ~162% jester's dps/mass
As you can see, a jester's dps is quite mass inefficient compared to its t1 alternatives.
Make jesters cost less mass (ie: smth in the 120 to 140 mass range, rather than 170). Even if jesters' mass cost is reduced to 140, it would still cost more mass per dps than all of the above T1 alternatives.
Jester with 140 mass cost: 140 mass, 50 dps -> ~0.36 dps/mass
Jester with 130 mass cost: 130 mass, 50 dps -> ~0.38 dps/mass
Jester with 120 mass cost: 120 mass, 50 dps -> ~0.42 dps/mass
I think such an improvement to jesters' mass/dps efficiency would make them a more viable choice without making them too OP. However, it may be worth increasing the build time cost in combination with decreasing the mass cost, to not make an early jester rush too strong.