I hear you about the extra work to learn the Fun 21 strategy not being worth it. I understand that POV.
But just to be precise, I believe that the house odds on the ship’s 3:2 standard blackjack (SBJ) are not 0.5% but, rather, 0.63%, what with six decks in the CSM, double down permitted after splitting but splitting Aces allowed only once, and no surrender permitted. See, for example, https://tunicatravel.com/blog/2017/01/two-deck-vs-six-deck-blackjack-games/ and also https://www.onlineunitedstatescasinos.com/las-vegas/blackjack/six-deck/
So Fun 21, when played properly, has the best odds of any game on the ship by a whisker. Fun 21 also has a smaller minimum bet than the ship’s 3:2 SBJ, which I like when I want to keep my bets small. But the most important thing to me is the hand shuffle. I won’t play any blackjack anywhere that is shuffled by a CSM. So I was forced to learn Fun 21 if I wanted to play BJ on the ship. One drawback to Fun 21 that you didn’t mention was that there are a few players who sit at the Fun 21 table who will groan when you do something “nonstandard,” like hit your hard 12 against a dealer 5 or 6. Its always a conundrum -- do you just let the groan stand or do you try to educate them about the effect of the kings missing from the shoe?? Its best, of course, not to say anything. But sometimes its difficult.