Product review (5 stars): Cheap! In a good way.
My Whirlpool washer was bought in 1995.  I have replaced this type of coupler five times now.  Bought several revisions over the years and this is the first time I bought one off the internet.  All my couplers have always failed the same way despite the revision level.  Wearing of the rubber that eventually broke off one of the plastic extensions.  This gives you a warning of the impending doom and complete failure.  The washer now has either a odd noise, vibration, or both.  It will get worse as more pieces start to break off the old part.  Soon the washer motor will run fine but nothing will move inside the washer.  Looking under the washer will confirm the failure with black chunks of rubber on the floor and possibly some bits of plastic.  For the ease of changing this out I stuck to the kind that does not have the metal insert. The metal insert does not seem to make a change in reliability.  The hubs never broke in the center and always fit tight so I do not see the all plastic design as the problem.  The rubber on the one I just bought here seams heavy duty and fits snugly (had some that were softer and fit loosely in the past.)  Only time will tell how long it will last though.  It will fail eventually, they all do.

Considering the cost of a repairman just to show up at your home, their price for the part, additional charge for labor, the average person would have called this washer junk years ago and would have just bought another one.  This only costs a few bucks and is easy to install.