As far as the cheap shackles being junk, they are still plenty good for anything you can do with a winch in an off road situation.
If I'm rigging for a crane, lifting where there is a real problem if things go wrong, I will buy Crosby rigging so I have no worries.
Fo recovery gear on a Jeep or any other 4X4 even the cheap ones will lift many times the vehicle weight without problems.
Another thing most either don't know, or ignore is the difference in rating between recovery gear and lifting gear.
Lifting gear is rated with a 5x safety factor, while recovery gear has only a 2x safety factor.
Shackles are all rated for lifting, so a 4 3/4 ton shackle has a mbs, or Minimum Breaking Strength of 47,500#
In testing, these usually go over 55,000#. A side pull on the shacle will cut the rating and the breaking point, but it is still nearly 40,000#
Also, the size, 3/4", is based on the bow, while the pin in the 3/4 is actually .88, or 7/8".
This explains why they don't fit the Factor 55
The synthetic rope many of us use is NOT rated for lifting. Most of it is rated for 10,000#, and the mbs is a little bit over 20,000#. They are using the recovery rating. This is another reason why you don't usually see it on cranes.
Whether you use a hook, shackle, soft shackle, chain, or a piece of rope, the safety of what you are doing comes from a good understanding of the proper use of each piece, and using each within the limits it has.
Below is a chart showing the info from Crosby for their shackles.
This choosing to use a Factor 55 might want to use a 5/8 shackle, since the pin is 3/4 and will fit the hole. That is still a breaking strength of 32,500# and for recovery would be rated at 16,000#
Here is a link to more useful information for those with time to kill
http://www.pacificmarine.net/marine-deck/winches-and-hoists/how-to-size-a-winch.htm