If used in moderation, and they are good spacers, i dont' think its a big deal. I like the idea of using them to make the front and rear track width's equal on an SFA truck, but on an IFS one, the front track width changes slightly with suspension travel.
Haven't got them yet. Should be here in the next day or two. You need to come down here for the weekend so we can do some snow wheeling. We got a lot of snow over the holidays, Plus I got a new video camera.