Actually; depending on sea state; once on plane any high performance boat gets very stable. At lower speeds; in full displacement mode they tend to wallow... but with those throttles cracked open, a PT's deck motion was dramaticly lessened and a good gunner could easily compensate for the rythym.. much smoother and slower than the motion of a tank over uneven terrain.
Three or four of these in a simultaneous evasive pattern attack will easily overwhelm the gun defenses of a AH destroyer or cruiser; and with 12 torpedoes in the water; the cruisers fate would be sealed.
Attrition on the PT's would be high... but the tradeoffs are obvious... if they get to torpedo range, life expectancys of the cruisers or destroyers diminish dramaticly. Yes.. we need the night!

Real life torpedo boat attacks were hell on the PT's.. and drove the Japanese nuts too.. ruining their defensive screen, and causing all kinds of panic and confusion on convoys. A daylight PT attack as part of the opening moves of a coordinated submarine and air attack left many Japanese escorts without a convoy to guard.
I'm looking forward to these.. could be a lotta fun.

Hang