Is the metal hardware worth the $20 upgrade?  Is it easier or harder to adjust, and has anyone broken the plastic?  Thanks.

For what it's worth my VCAS slings have been through 3 classes and had no issues with plastic hardware.  The instructor highly praised the VCAS but made no mention of spending the cash on upgraded metal hardware.  At least one other student had the exact same sling as I had and also had no issues.

I sleep just fine at night with my plastic hardware slings.  Including my new VTAC bungee sling.

Having seen literally hundreds of the things get abused way worse and for far longer than you have time for (assuming you don't drag the stupid thing behind your truck)... you will not have an issue.

I've seen one of them break, the slider portion cracked. I think it got caught on something while a guy jumped down from an AAV.

One, of hundreds...

However, I would personally spend the extra $20 on metal. That's just me. If you can't afford the $20, don't worry about it, but if you can afford it, it's cheap insurance.