I'm in the camp that says: No straight islands!

There's the historical-accuracy-argument going on, as well as a minor gameplay argument.

1. Historical accuracy -wise, it's obvious; the English Channel for example, and how it has protected them against a lot of bad things, from Armada to Napoleon.

2. Gameplay. Not as much turtling. And re-emerging factions get back in the mix.

Regarding 1, I feel that AI fleet management and naval combat is too random to properly reflect the power relations that you assign intuitively. In this particular case, a nice solution would be to make the land bridge a one way into Flanders. This would let the English get some time and space away from the French.

Also, I don't like the H-A argument to go too far. There's a point where H-A just smothers gameplay - something that inevitably guides every debate on improvements/changes/modifications. For me, it's OK to limit the landbridges to go from island to mainland/larger island. The small factions will be safe for a while (H-A) but able to, in theory, invade and grow somewhat (Gameplay).

Regarding 2, I've mentioned the benefits in the above about one way bridges. The fact that re-emergants will get back and be relevant speaks for itself. Ultimately, I want more action and these one way bridges supply that. If H-A suffers - so be it. It doesn't suffer to the point that it affects gameplay negatively. Quite the contrary in this instance, actually.

Was it you, Macsen, who first talked about this long ago?