1) Extend both Resto fields AOE x2 (10->20) + fix behaviour bug (see bug report thread). Then it's easier to use because the units gaining benefit from it don't have to be just near the ACU (bumping / pathfinding issue that makes micro difficult) and you don't have to care about veterancy.
2) ACU chrono amplifier: give it a more reasonable cost something like 2500-3000 mass / 150000-200000 energy =(a bit more exepnsive than Aeon Chrono dampener) but not more than Cybran laser. Reminder : this weapon (4500 mass) costs currently more mass than a maser upgrade (4000 mass), but adds only 300 DPS and an AOE of 2. Maser adds 4000 DPS... No comment.
3) T2 Hover tank : modify the current weapon cycle (175 damages every 4 secs) to: 50 damages every second (almost same DPS as before, but better firing cycle).
4) T1 Sub : 7 seconds reload for the anti-torp weapon instead of 20 (!). Or leave the same poor anti torp weapon and give them 500 HP instead of 400 (for comparison, UEF sub = 600 HP, Aeon = 550 HP; Cybran = 525 HP).
5) T2 navy : allow Seraphim latest tier Sonar (T2) to move.
6) T2 Sera torp bomber weapon same as the other factions (= not vulnerable to anti-torp weapons).
6 moderate changes, no more, and Seraphim would be roughly on par with all the other factions on all the maps.
What do you think? Are these reasonable enough?
EDIT: I forgot about the t2 sonar that should be able to move since Sera has no t3 sonar able to move.
EDIT 2: I replaced Sera Destoyer HP buff by "T2 sonar being movable".