"... NWN is unusually well-balanced..."
Yes, relatively true, and one of the things I like about the game, since it is disappointingly rare. In NWN it is actually kind of/sort of possible to make modules balanced for most reasonable classes, if you are not too perfectionist about it. I do not think I could do that in NWN2, for one example. In that game Clerics are even more insanely OP, among many other balance issues.
I don't think I will pay Sworflight...
It can be rather intimidating, and even the strongest classes and players can go down quickly if they get careless, but I have included some "safety valve" features that should make it possible to complete even for someone who is not a master of combat tactics. I think one of the reasons people struggle with it is because they tend not to take advantage of features like the Respawn system (and in Ch. 2+ you can choose an easier setting giving you more Respawns for a lower penalty) or Rest Runes, due to the modest XP penalties. I have found that many players have an irrational fear of losing experience that is out of all proportion to its actual value, especially in a module with farming opportunities that can be used as needed.
Just completed everything in the Forest of Mir (Swordflight), a few observations for the forest itself (not the fortress, the fortress is fine) and a strange occurrence ...
1. Not specifically intended so much as it was hard to avoid and I was not especially interested in avoiding it.
2. I think some of this at least was because I was trying to put non-hostile creatures in separate ares from those with hostile encounters to avoid the two running into each other and creating various complications. It might have been a good idea to put a fast travel option back to the village from the fortress, but due to the non-linear layout you can clear the fortress before clearing some other areas, and I think I wanted to discourage players from leaving quickly without exploring everything.
4. The Satyrs are mainly there as an opportunity to use conversational skills if you have them. Encountering them will probably not end peacefully if you do not.
5. See answer to 1, above.
6. Only reward is the minimal XP, and the satisfaction of seeing live soldiers about the village later. It is indeed hard to save them so maybe it should be more rewarding, but for the same reason I also did not want to make saving them too important.
7. I think I intended it to be a little humorous - these poor villagers think that something that is a dime a dozen for a typical adventurer is a great reward. Of course, the real reward for the quest is all the loot you take off the bodies of your enemies.
Equipping cloaks causes wings to become invisible. Some players actually like that effect, since they think the wings on RDDs look silly, and that is usually the only context in which it is relevant. Presumably making cloaks invisible does not alter this feature of cloaks, whether by accident or design.
Actually, I considered a Shifter for Swordflight. The most fun I ever had with an NWN module (and I've played hundreds) was as a Druid/Shifter in Saleron's Gambit. And, oddly enough, it was one of the most overpowered - if not the most overpowered - builds I ever played in an NWN module in the final battle.
That is because Saleron's Gambit was a very low magic module series. The trouble with Shifters is that it is very hard to balance a module for them without unbalancing it for every other class. If the magic level is too high, players will have access to gear providing greater powers than the Shifter forms, making those forms redundant and useless. If it is too low, Shifter forms will be overpowered (e.g., a form with Damage Reduction in a module with no or only very low-level weapon enhancements). It is certainly possible to play Swordflight with a Shifter, and since the series is not extremely high magic there could be even worse environments for them. Also, like every class they do have special advantages (e.g., any needed elemental immunity) in particular situations. However, based on my own playtesting it is one of the hardest classes, if not the hardest, to play there. Of course part of that might be due to the fact that I do not play the class that often and thus am not too expert with it.