iv heard of the vg 6000 all over and have owned one myself, sorry but iv never heard of a Tracker III, as for build quality my ex girlfriend threw the vg6000 down the stairs and it hit every step aprt from the second to last step about 15 in total. and it still worked had to buy a new ariel but thats nothing, if the tracker 111 can stand being thrown down the stairs and still work then it sounds good.
as for looks i choose the vg 6000