Borderlands 2: Proposed Commando build with lvl 50 cap

Just making some notes on a build.  Nothin' fancy.  These are also how I have them planned in order of procurement.

• Preparation 5 (+3% shield capacity per level; regenerate 0.4% health per second per level when shields are full.)
• Ready 5 (+8% Reload Speed per level)
• Impact 5 (+4% Gun Damage and +3% Melee Damage per level)
• Willing 5 (+15% Shield Recharge Rate and -12% Shield Recharge Delay per level)
• Expertise 5 (+14% weapon swap and aim speed per level; +7% movement speed when aiming per level)
• Metal Storm 5 (Kill Skill. Killing an enemy gives +12% Fire Rate and +15% Recoil Reduction per level for a short time. )
• Steady 5 (+8% Recoil Reduction, +5% Grenade Damage, and +4% Rocket Launcher damage per level)
• Onslaught 5 (Kill Skill. killing an enemy gives you +6% Gun Damage and +12% Movement Speed per level for a short time)
• Scorched Earth (Adds Multi-Rocket Pods to your Sabre Turret. 22 Rockets per Volley)
• Grenadier 4 (extra grenade per level)

Of the three skill trees (one focused on turret, one on direct engagement, and the last defense) I'm least impressed by the defensive - at least for solo play.  The Preparation skill is pretty damned useful but I don't think I'd put any more points than that into defense.  I'm playing this as more of a hit and runner, with an emphasis on grenades, getting maximum reload and accuracy from weapons, and having a fast recharge on shields.  I am strongly considering Able (Damaging an enemy regenerates 0.4% of your Maximum Health per second per level for 3 seconds) in lieu of Scorched Earth and Grenadier 4 (then picking up those two when the level cap increases).  The main reason for considering Able is simply having the ability to stay in the fight (particularly in arenas or big fire fights) and unlike Quick Charge (Kill Skill. Killing an enemy regenerates 1% of your shield per second per level for a short time) you just have to cause damage.  Do or Die (Allows you to throw grenades while in Fight for Your Life. +10% Grenade and Rocket Launcher damage) would be nice to round out the grenade damage.

What fit are you leaning towards?