Had the parallel guides with extensions and sold them. I have a very small shop and they took up entirely too much space because I had to hang them off of my MFT (extensions) and then support the dangling end with another table or saw horse. Way too clumsy and my cuts always seemed to be off, especially when I got to the end of a piece of stock. And then the guides always tore away at the grippy strip things on the bottom of the rail. I went whole-hog into the festool PG system without much research because I didn't know about the rip dogs, precision dogs, and seneca systems.
Like others, I eventually opted for one of the third party systems that utilizes the incra t-track plus. I have yet to use it, but I already like the fact that it's smaller and easier to move/store in my shop and it supports the material being cut unlike festool PG extensions.