One thing that some of you youngsters may not realize is that "tracking" was used in the 60s to create defacto segregation in many schools all over the US.
Tracking was placing kids into tracks based on kids' presumed abilities. Well, whenever people are grouped - the bias of the grouper enters in. If someone has more sinister puposes, its pretty easy to put who you want into which track. there are lots of stories of first and second generation immigrants of many races being kept out of the "good tracks" in California for instance.

Ability grouping has an unpleasant association to it for many. If you go in with ability grouping guns blazing you may open old wounds and get reactions you don't expect.

In reality, ability grouping won't help most of your kids anyway. If you have a six-sigma kid (unless you are in a tremendously sized school district) even if you are ability grouped you are going to be grouped with only three-sigma kids at best. It still doesn't put them with cognitive peers.
It may "remove the bottom" as someone said, but the elitism that some see in this type of tracking may not even be worth it. Besides it's hard to get away from associating worth with ability in these situations. how would you feel if your kid was in the removed bottom? are high ability kids worth more than IEP kids?
It may be better to talk about FAPE and what is appropriate education for each individual. If you want tracks so that your kid doesn't have to be with the less able, well that is elitist, and some are going to be resentful that some peoples' kids get something better than their kid does. Sorry Mrs Jones but little Sally just doesn't qulify for the "full success" track. She's only average. She has to stay in the "average track" with others of your kind...

But if all you want is for your kid to get an appropriate education, well who can argue with that?

Advocating for an appropriate eduction for all might be even more effective. Even a near-perfect small school district can't be expected to know how to meet the needs of the kind of kid they may see only once every 20 years or so. However if school districts were more focused on reaching kids than test scores then when they see this twenty year kid, they might be able to plug into some type of nationalized resource network for help in meeeting her needs.