just a thought but how well does the squaring of the gantry work when the gantry is solid enough to stall a stepper
The gantry should be installed as square as possible. If it's out of square, and the motors aren't strong enough to push/pull it square, then it's not going to work.

Squaring the gantry imo is not the main reason to use dual drives. Dual drives keep it from racking. Most larger DIY gantries will rack rather easily, until you get into the big all steel ones that weight 300 lbs or more.