Hi Daniel,
The BlueROV2 is a high power vehicle that often undergoes quick movements in all directions, where a thruster can draw up to 25A. It also uses the Basic ESC R3, and we have never experienced any issues with the ESC during many hours of real world dives. In fact, we have not yet had a single customer report of any issues with the ESC; it has been included with every BlueROV2 and most thrusters shipped in the last 3 months.
I tested the Basic ESC R3 thoroughly before we launched it, and was unable to cause a single one to stop working or otherwise malfunction while running our thrusters, short of pointing a high power heat gun at it while it was running (it was fine once it cooled off). For more details on the tests I did, check out the first post in this topic. The Basic ESC R3 does already have about 110µF of capacitance in the form of surface mount capacitors. It certainly doesn’t hurt to add more, but given the proven reliability, it is unnecessary. If you do still want to go ahead an do this, an additional 220µF across the power and ground of each ESC at the PCB would be plenty.
-Adam