Poly has some issues when used for LCA bushings. One is location - that can be addressed by the front bushins on the strut (where they attach to the K). Some photos and drawings on my website. Best is to dry fit, then cut the poly bushings to the right size. Slight differences in the struts and lengths on later As which I don't recall off the top of my head.
Other issues with poly is yes the squeak (althought th polygraphites werent as bad the one time I used them) and permanent deformation or wear under extreme situations (had that myself on a different set). Nylon requires some extra effort on installation. That's what I'm using now with greasable 'pins'.
With nylon you will feel the road a bit more! I've got leather wrap on the steering wheel and on a rumbly or rough pave like the NJ Turnpike your hands will be getting a constant vibration. This is with 70 series Firehawk Indy 500s - an M&S rated tire. But I'm still happy with the decision - but I would not recommend it except for the most serious sports car experience. For serious autocross or vintage racing - do it, but know the price.