Obviously as a rep for Poly Performance im going to tell you they are the best bang for the buck, which I honestly believe. You might take a look at the last few pages in this thread http://www.jkowners.com/forum/showthread.php?t=34227
Synergy ball joints take some serious abuse.
They use a cromo ball with a bronze race.
They are not rebuildable.
We have guys running these in daily driver applications with 37's & 40's but we also have a more than a few guys that use their JKs solely for offroad with similar sized tires.
We have had 99.9% positive feedback.
With exception to the break in period. The ball joints are tight on initial install & will take a few 1000 miles to break in, once broken in they will give a much tighter feel than stock & eliminate the clucking.
You will see a much longer lifespan then stock with the Synergy ball joints.
As of this point there are thousands of JK balljoints in use.
As luck would have it, we also sell the Dynatrac components,
They are also a very nice piece, i dont think you can go wrong with either companies product.
The Dynatracs are rebuildable.
Again i havent seen any premature failures with Dynatracs components.
The price is the only downfall.
Hope this helps!