Having now turned my attention to actually
playing GWX 2.1 (with SH3Cmdr R3.1.2 and wow, if I may say so myself, what an experience), in consideration of
restraints such as hard code limitations imposed by SH3 (and there IS a lot - static behaviour for all years is just one of many, and one reason why SH3Cmdr exists), I have to say that I'm not sure we could get anything better. No, GWX 2.1 is not perfect, but I don't see anyone saying that it is. I'm now in mid-1940 having started in Aug 1939 and with discipline, I've had good success. I've watched enemy Destroyers totally miss me even though I wasn't that far away. Why? Because I'm disciplined in my approach and use what I consider effective evasive measures. And in times where I have been bounced, as frustrating as they were, it was because of my own stupidity - staying surfaced, conning tower breach, or some other stupid behaviour of mine.
I may not like being seen many kms away in dense fog and then watching the Destroyer make a bee-line for me only to pound me into oblivion, but conversely, I don't like sitting on the surface waving to the enemy either while they earnestly look for me. Although on this last point, one convoy I attacked I sunk three merchants and the escorts went straight to where I was and hung around there. Of course, I was on the other side of the convoy at that point laughing at them, so evasion is possible and not that hard if you know what you are doing, at least in the early years. Come 1943 things may be different, but so too will my tactics.
Just my opinion, ymmv.