From: PDX (and now) London, UK
One of the things that I noticed by playing in a PBEM game that considerations about fuel efficiency is one thing, the thing that one needs to consider is the point value of loosing high value AKs vs sending a bunch of 1pt xAKLs into enemy sub patrolled areas.
Yes. There are a lot of factors to consider though!
Which ships are more likely to survive against a sub screen and race past, like the 18 knot AKs. Which ships offer compatibility of speed with the best escorts? If sunk how much fuel are you also losing in the bunkers of those ships, and how much of whatever cargo are you losing? You could also say it's better to lose a 3 VP ships and a smaller percentage of the cargo for each TT hit than what would be on a 20 VP ship!
For troops I usually prioritize high value fast, efficient cargo and troop ships. I rarely send troops any distance longer than 20 hexes on an xAKL, especially through the open ocean. Close in though, the smaller ships may have an advantage as even aggressive commanders often 'elect not to attack' the tiny xAKL/PB types.
In game terms I'd really consider the time period, how torps are working, what type of subs frequent the area, how good the ASW air is and can you travel under its umbrella, and do you have plethora of the E escorts ready to patrol the area?
In my Japanese game currently going I'm suffering a bunch of losses as it's later 43 and he's being really aggressive with the USN subs near the HI now. I don't yet have a lot of Es and the ones I do have are assigned to TK/AO, so the troops get converted minelayers/minesweepers, the faster TB, and PB. It's pretty brutal, but I didn't feel quite right in my first game killing half of the Allied subs either. This feels like it's a duel and I like that. He adjusts and so do I and neither of us has yet begun to dominate this part of the game.
"Success is the ability to go from one failure to another with no loss of enthusiasm." - Winston Churchill