In that 5-8 IPC range, how much of that range is influenced by the skill/desire of the player(s)?
That range is determined by the lowest bidder, not by what the players perceive the balance point is. I believe there is a difference. Lets say a skilled player believes he/she can win with the Axis with a bid of 6 but as the bidding process goes it stops at 8 because the other player is not willing to take 7, because they believe they cannot win as the Axis with 7 or they just want to play as the Allies or they want a challenge. Therefore, the bid is 2 points above the first players perceived balance point and may or may not be below the other’s.
I would not be surprised if it was really at the lower end of that range.
Perhaps we should have a poll for this. I did a few searches for “min bid axis” and “axis bid poll” but didn’t get any hits. I’d be careful of the wording of the poll question. You want to stress that they choose the bid value where they think it would be an even match if they played someone with the same skill as they have. You may want to allow them to pick 2 or 3 values so they could give you a range.
Another option would be to do the cold, hard math and collect the statistics from the forums and other sources. Record what the bid was and what the outcome was and do the various calculations like mean and mode or what have you. By watching the percentage of axis wins at a bid value you should get an idea of where that balance point lies. By focusing on the outcomes it should minimize the affect of a player’s desire for a challenge.