Updated version is here:
https://spreadsheets.google.com/ccc?key=0AoGF0nJQdKAOdEtJQVZ0ajd3bFVwZnU1ZmxzR09Zb1E&hl=en

Or here:
https://spreadsheets.google.com/pub?key=0AoGF0nJQdKAOdEtJQVZ0ajd3bFVwZnU1ZmxzR09Zb1E&hl=en&output=html

  I don't know which version is "prettier" but I updated it by calculating the value of a free FP.

  Basically, I took the value of invoking an Aspect and divided it by the average length of a battle. I calculated the value or a re-roll  and divided it by the average length of a battle.
  Also, I renamed O-Aspect and D-Aspect to O-Stunt and D-Stunt, since an Aspect Requires a Fate Point and Stunts do not.
  I did tweak some of the maths, but it didn't change the values much.

  Also, I did "try" and calculate a 2-on-1 battle and it seems like the numbers scale well-enough in multi-player battles.

  If you click on the tabs, it should help you see the maths behind the values. Let me know what you think, ok?

Iago, et al.
  The only reference to throwing distance is in the description of the Good Arm Stunt (YWp156).
  And this seems perfectly reasonable to Mortals.

  But, I think Supernatural Strength thould affect throwing Distance as well. But it is not stated. So in this scenario, even a character with Mythic Strength can't throw ANYTHING as far as a Mortal with the Good Arm Stunt?

  I dunno, it seems confusing to me. Is that right?

Belial,
  You mean to tell me a character with Mythic Strength can't throw things more than one zone? That doesn't sound right at all...
  I'll have to look that up, because that doesn't make sense.

Belial,
  Well, maybe that is just a matter of tactics? I mean, the Speedster has a gun, the Bruiser doesn't. But with his massive strength, can't he throw for tons of damage?
  I guess I can add a Range metric and a movement metric. It wouldn't be that hard, I just wasn't sure if it was a factor in Fate...

  Also, I don't really know the rules for grappling. Or how often it happens in real play. In other games I have played, Grappling was overly complicated and avoided in combat because of its general lack of effectiveness. Generally, Grappling only has the effect of disabling the attacker and the target. Useful in some cases, but not many.

Bruiser
+4 Althletics, Fists (+3 from Strength)
+3 Endurance, Alertness
+2 Might, Discipline
+1 Presence, Intimidate
plus Mythic Strength as power.

Physical Rating: 72 = 0 (1xAlertness) + 18 (3xFists) + 18 (3xStrength Damage) + 20 (5xAthletics) + 16 (4xStress)
Social Rating: Not enough info I think, but based on the info provided, 15 = 0 (1xEmpathy) + 3 (3xPresence) + 0 (5xRapport) + 12 (4xStress)

Speedster
+4 Althletics (+3 from speed), Guns
+3 Endurance, Alertness (Equivalent to +6)
+2 Might, Discipline
+1 Presence, Rapport
plus Mythic Speed as power.

Physical Rating: 78 = 9 (1xAlertness) + 12 (3xGuns) + 6 (3xWeapon 2 for gun) + 35 (5xAthletics) + 16 (4xStress)
Social Rating: Not enough info I think, but based on the info provided, 20 = 0 (1xEmpathy) + 3 (3xPresence) + 5 (5xRapport) + 12 (4xStress)

  Looks like they are pretty evenly matched. Speedster has an edge. More so if he can tag the Bruiser with Aspects if he can engage him socially before the physical conflict breaks out.

EXAMPLE:
Two characters are facing each other, are they balanced? Let's find out:
I Lung
https://spreadsheets.google.com/ccc?key=0AoGF0nJQdKAOdEFJRnJRVExueGxjSGxXOWw0dWZoemc&hl=en
Pertinent Data:
Relevant Skills:
Alertness: 2
Athletics:
Empathy: 2 (+1 for Mark)
Fists: 5
Presence: 6 (+1 for Mark)
Rapport: 5 (+1 for Mark)

Physical Weapons: None
Social Weapons: None
Physical Armor: None
Social Armor: None
Physical Stress: 4
Social Stress: 4, +1 Consequence

Aidan Berringer
https://spreadsheets.google.com/ccc?key=0AoGF0nJQdKAOdGc3RzJiYU5GVm9qanBJRVF6dnJKaFE&hl=en
Relevant Skills:
Alertness: 4
Athletics: 3
Empathy: 0
Intimidate: 1
Presence: 3
Rapport: 0
Weapons: 5 (+1 for Sword)

Physical Weapons: Sword (Weapon: 2)
Social Weapons: None
Physical Armor: None
Social Armor: None
Physical Stress: 4, +1 Consequence
Social Stress: 4

Comparing Values in conflict:
I Lung:
Physical Rating: 48 = 2 (1xAlertness) + 15 (3xFists) + 15 (5xAthletics) + 16 (4xStress)
Social Rating: 63 = 2 (1xEmpathy) + 18 (3xPresence) + 25 (5xRapport) + 16 (4xStress) + 2 (2xConsequence)

Aiden
Physical Rating: 62 = 4 (1xAlertness) + 15 (3xWeapons) + 4 (Aspect from Holy Touch) + 6 (3xSword) + 15 (5xAthletics) + 16 (4xStress) + 2 (2xConsequence)
Social Rating: 25 = 0 (1xEmpathy) + 9 (3xPresence) + 0 (5xRapport) + 16 (4xStress)

  So, based on that, I Lung has an edge in social conflicts and Aiden has an edge in physical.

  As a GM, you can use this information to balance encounters to meet the strengths and weaknesses of the characters involved.

Basically, I calculated how much changing one stat effected the damage per turn and how long the conflict would last.
Then compared those values relative to "Average" characters in a conflict.
https://spreadsheets.google.com/pub?key=0AoGF0nJQdKAOdEtJQVZ0ajd3bFVwZnU1ZmxzR09Zb1E&hl=en&output=html

Note: "Technically" these calculations are conflict-type agnostic. Meaning they should be the same for Social and/or physical conflicts.

Please let me know what you think or where my calculations are flawed.

Yeah, with 8 players, there is no way I am going to ruin it as multiple groups. Not only wlould it be painfully boring for the non-active group, but it would be nigh-impossible for me to keep it all straight...