I don't have experience with them on my personal car, however I have some friends running them in their track prepped Miata. One thing to note is that they expand with moisture, and the expansion has to be taken into account when being machined or they will crack/seize. Just thinking to myself that you may have issues if you try to change the caster too much. If they are machined to fit your particular setup I believe they will work well, but if you deviate too much from those specs the Nylatron wont allow much movement. For a similar cost you may want to look at getting a spherical bearing pressed into the control arm, as this would allow you to retain your current arms but with more freedom of movement. Just thinking aloud :)

Actually, I did use Heim-jointed lower control arms for several years.  BUT, you had to pull the pin to adjust the Heim joints and that really po'd the alignment shops.  So I went to a newer type of control arm that works like a turnbuckle.  You just loosen the two jam nuts and then adjust the center section to get the desired camber before re-tightening the jam nuts.  Here's a link to the arms that I'm using:  //www.gbcarparts.com/proddetail.asp?prod=SU-AdjLowerArm
As you can see from the photo, the arms use poly bushings.  The ones shown in the photo are yellow but mine were orange.  At any rate, all four of the bushing halves cracked after a few years of hard autocross use.  I've ordered and installed some up-rated black poly bushings (21A1882MS) from Mini Spares but I'm seriously thinking about moving from poly to Nylatron for the added strength and built-in lubrication.
I just need to know if anybody else has experience using Nylatron bushings before I spend the big bucks to have them made for me.

 Apologies if my response was too general. Good to know a little more details regarding the question. I'm assuming you are not considering running rod end bearings due to class limitations?

Interesting, indeed.  That's why I posted my original message.  My car is a dedicated SCCA autocross car and has been for almost 30 years.  I don't care how it handles or performs on the street because it's a trailer queen and never sees street driving.  I just care about what it's going to do under competition conditions.  I've used all kinds of lower control arm bushings both rubber and poly, with fully-adjustable lower control arms, and I've had mixed results.  My last set of poly bushings cracked.  Now I have the opportunity to have some Nylatron bushings custom made for my car and I'm interested in hearing what others who have used them have to say before I spend the big bucks to have them custom-made.  

Indeed............thats interesting................!!!!!!!!!!!

In my experience both nylon and poly bushings are designed to try and accomplish the same function. That is to allow the control arm to rotate freely on its desired axis. They are therefor working in the same way that a heim joint works, but with varying degrees less harshness (depending on the stiffness of the bushing) for road use. This is unlike rubber bushings which twist and add spring rate while doing so.

The problem with poly bushings is that if they are not made to fit in the control arm precisely, and lubricated often, they will bind and cause worse handling then without them. I have also seen many times that the bushing will dry weep, and become oblonged in the race over extensive use. The nylon bushing don't go out of round, but will bind up if not machined correctly, and due to their stiffness they are only marginally less harsh than proper heim joints.

Rubber bushings on the other hand have quite a few positives going for then, particularly when using the uprated durometer ones. They retain their shape even after decades of use, never squeak, never bind, and have more of a manufacturing tolerance. Its the reason that oem's use them. The rotational spring rate can also be of a benefit to anything but the most serious race car. The added spring rate works in a progressive way to add suppleness the suspension under light loads, and tighten up as the impacts get bigger.

For these reasons I always go with uprated rubber whenever possible. If stiff rubber bushings are good enough for Porsches and Ferraris they are surely good enough for our little minis! :)

Does anybody with a competition Mini have experience using Nylatron instead of Poly for lower control arm bushings?  Pros?  Cons?