The 9 inch rims maximize the contact patch and seem to minimize sidewall flex, but this was the result of Brian's recommendation, not any personal experience working with 8's vs. 9's. I think for a steet only application, the 8 inch rims will present a nicer / fuller looking appearance to the side wall of the tire that most folks may find more appealing. However the 8 inch set up will still provide excellent aggressive street performance.
The end links, I still would do the on-the-car adjustable units, the cost savings is not sufficient to me to warrant going with the RB units, if I was going to do this all over again. As you get more into this stuff, you may find your objectives / goals with the car change, as such you will not have to change the links to adapt. Remember every time you change something on the cars running gear, this may have an unanticipated affect on handling you may want to adjust for, why limit yourself. As I move forward with my own goals, I will let you know if these items are available.
Good luck with your future driving experiences, but be aware this stuff is addictive!
Pat- Va MX5
2012 MX5 PRHT GT