I made the decision to switch the soft rigging whenever possible years back. As most aftermarket recovery points have yet to properly accommodate soft rigging, I still carry a few steel shackles in the bottom of my bag. I do cringe a lot on the trail when I see people haphazardly using soft rigging on sharp corners. While you might get away with it for one of two pulls, it will significantly shorten the life of that gear. That brings up another point I see a lot.....
Vehicle recovery gear is not a forever item. While people might try to treat it like that, I see lots of gear both hard and soft, that should be retired. Gear inspection and retirement is a hold over from my days falling out of a helicopter on a rope, it is also common in just about any commercial overhead lifting program. Just because it is steel, doesn't mean it lasts forever.
I make most all of my own recovery gear, including soft shackles. For a 6000lb vehicle you should be looking for a unit constructed from a 10mm or 7/16" Dyneema, something SK75 or Amsteel Blue. A properly done unit in that size material should have a MBS (Minimum Breaking Strength) of more than 40klbs. I look at most 'drag' recovery ( not overhead lifting ) with a FOS ( Factor Of Safety ) of 2-4:1 depending on what type of device it is. A soft shackle is going to see the most wear in the system typically, so 4:1 is more applicable. On a synthetic winch line, 2:1 is going to be about all you can reasonably do.
A quality soft shackle is going to be $30-40+ typically.