I have several sets of both Impact and Kenny Kong tracks.

The advantages I see to the Impact tracks is that the locking pins stay in the tracks very well, and they are easy to darken by soaking them in white vinegar for two hours and then rinsing them off. The only disadvantage I know of is that you have to buy them through Mitosal, and their postage costs have always been far higher than what you would think is necessary. It is the one reason that I do not buy from them more often, and would buy from any other dealer who stocks their products, first.

I bought my first set of Kenny Kong tracks in about 2003, and have around 8 or 9 sets. I like what he makes, and his marketing person on the Bay (called Manheader) has always been friendly and helpful. Sometimes, he is the only manufacturer that produces the type that you might want (KT transport tracks and Pershing T-81 tracks with sprocket come to mind). The only disadvantages I have found with his tracks are that they are more difficult to darken by soaking - I have not yet found something that will work on them. And, sometimes there is a problem with them corroding and crumbling - I believe the problem is called "zinc pest." In my experience, his tracks come in two different "colors." If they are a very shiney silver color, then they probably do not have the corrosion problem. But if they are a darker, more dull, and lead-colored; then you will have to watch them for that. I have had two sets of Tiger I tracks have this problem (combat and transport - which he no longer makes). Both of them only sat on a shelf, and the tracks did not turn. After about 4 or 5 years of shelf-life (pun intended) the tracks broke apart in multiple places when just trying to revolve them by hand. I do not know if they have fixed this problem (maybe they have, and that's why the most-recent track sets I have bought are all shiney); but I still like their products, customer service, and shipping costs. I will buy from them again.