To add a contrary view to length choice, I am at 5'9" 175 lbs and found the MX83 173 much too short for my liking / ski-style.
I'm also picky on mount point so I always put on a demo-binding -> Attack 13 demo ( K13 demo in Kastle-speak ).
I'm more about finding the right mount point for ski engagement, per my ski style and body weight/dimensions/strength, vs having the utmost rock-solid interface from binding to ski.
MX84 is now available in 176cm , but now also has slightly shorter radius than MX83.
Scott's review stated it is the best ski he has ever set his feet into.
I personally have never gone wrong following Scott's advice.
But Scott has his remaining Monsters on for $399
A new MX84 flat will be probably 2.5-3 times the cost ( MSRP is probably $1200-1250 ? )
That's a big gulp from Monster to MX84.
[/ I have seen several reviews where the binding mount was moved forward on the 88. Either ski I will mount an attack 13 Demo so that I can play with the point.