I believe you are going about the calculations for average damage added per swing slightly wrong Moogul. In addition to the various attack table outcomes, I believe that ignoring the increase that heroic strike brings to a portion of your mainhand swings is important when considering the added value of an extra swing versus a crit.
This means that for offhand attacks, the calculation for average damage remains the same as posted above, (avg. hit damage) * (1 + crit - miss - dodge), as well as taking into account glances. I believe the glance rate is 20-25%, and reduces damage to ~70%, but someone can correct me on that if it's wrong.
However, the formula for average damage from a mainhand swing is going to be more complex. We first need to know the ratio of normal swings to Heroic Strike. Once this number is determined, the average damage per MH swing will be [ (avg. hit damage) * (1 + crit - miss - dodge - glancing_reduction) * (%normal attack) + (avg. HS damage) * (1 + crit - dodge) * (%HS) ]
Pinning down the average number of MH swings that end up as heroic strikes is a bit difficult, but I'll simply estimate one in three, as this is a conservative estimate for my own gear and group composition. With that assumption, as well as the 18% miss, 3.6% dodge and 45% crit you used in your examples, as well as the assumption that glancing will result in ~7.5% lost damage(25% of swings deal 70% damage) we get the following:
[ (avg. MH hit damage) * (1 + 0.45 - 0.291) * .66 ] + [ (avg. HS hit damage) * (1 + 0.45 - 0.036) *.34 ]
[top] avg. MH Swing
[ (avg. OH hit damage) * (1 + 0.45 - 0.291)
avg. OH Swing
That said, I'm having some difficulty fully following this through. Heroic Strike adds a static amount of damage to each swing, which means that solving the above expressions by canceling out the average hit damage term as Moogul did won't tell the whole story. Additionally, we need to know what percentage of damage is coming from the offhand, and what is coming from MH/HS.