I can't comment on the Eibachs, I just know that lip on both of the 15mm H&R spacers I had on my front wheels, broke off within a month of putting them on. That month did include a track day and an autox event, but that should not have been an issue in my opinion. I just know I will never get 15mm H&R spacers again. But I do believe it's an issue with the 15mm ones in particular and not so much the other sizes. The contact area between the actual spacer and the lip is very thin and therefore fragile.
And about tracking your car, be carefull what you say, do it once and you're hooked...
