I voted for the Developers to expend more effort on Performance. As one of the poor folk who is still stuck with XP (and likely to remain so for the foreseeable future) I have a vested interest in hoping that you will make a big effort to program Fallen Enchantress to run smoothly and quickly (or at least as quickly as possible) on the more primitive platform.
However, I think the point is pretty valid overall. Once you sell FE to all the power users, modders, hard-core wargamers, and hard-core strategy (including 4X fan) gamers, you will still want to reach NEW consumers, and more casual PC gamers. I am sure, ALREADY, that this game is going to be hugely successful with your core audience of Serious Gamers. Reaching a wider audience should also be one of your major goals, and those folks don't always have the best equipment.
I have actually played the FE Beta 2 for about 20 hours in the past week. It was a good week for me (free-time-wise); but the shocking reason for my playing so much, was that the basic game looked so totally inviting. It impressed me greatly! This is a game with stunning potential!
That said, I have two other pleas to make. First, please don't expend so much effort on making a "crushing" AI, that you neglect all the other aspects of the game. I understand that Mr. Wardell has a particular interest in AI; but I hope his personal interest in this one aspect won't siphon off useful resources, that could be better spent on other aspects of the game. Second, please make sure that your game has at least one or two fairly "easy" levels.
Over the years I have played a number of 4X games that had 5 or 7 or more levels, but I usually end up playing on the easier ones. (I remember one game - from a different company - that had NO genuinely easy levels. I came to hate that game; and I eventually resolved to stop playing it, and to think twice before ever buying another game from that company.)
I believe that for every hard-core player, who only wants to be "challenged", to play at the "ridiculous/suicidal/masochist" level, you can have: 3, or 5, or even 10 players, who just want to play at an easy/fun/casual level.
I realize that you have to appeal to the hard-core gamers; but you don't want to write off the larger number of non-hard-core players. The solution seems simple enough to me: create 5 - 10 "impossible-to-insane" levels for the former folks, but just don't forget to include 1-3 levels for the latter folks too. You really don't have to shoot for "lowest common denominator" -- but you really should aim for SEVERAL useful, POPULAR, denominators.
I love what I see so far! Please continue to improve performance in so far as practicable ... and aim for MULTIPLE audiences. Succeeding at those goals would constitute a seriously major achievement! I also think that would guarantee a highly profitable venture for your company!