I know that I had the USA Redump version of Lords of Thunder, but I went ahead and replaced it just to be sure that the problem isn't with the image. I'm getting occasional black screen resets, but mainly random freezes where the visuals freeze and the music continues to play. I've tried to play through the game maybe a dozen times, always resulting in a screen freeze.
So far, I haven't had problems like this with any other Sega CD, Genesis, Master System, or even MD+ game on the Mega SD. Usually, Lords of Thunder freezes during the game near the end of stage 1 or even during the first boss fight, but I've had freezes as late as Stage 3. I've never gotten past stage 3 without a freeze, just playing the levels in the order given by the game.
I'm on firmware 1.04 R09 playing on a US model 1 Genesis.