I've had both Roush and Eibachs. They are both technically made for the SLO, but are still stiffer than stock SHO springs and are perfectly fine on the car.
Both lower the car essentially the same amount. Eibachs will sag an additional 1/4" or so after about a year.
Roush definitely ride rougher. After 3 years with them on New England roads, I had to get rid of them and switched to Eibach. I've never regretted that decision. Car is nice and low but rides stiffer than stock but still decent. Both springs handle the same.
Both are discontinued, so finding them will be a challenge but there are definitely sets out there if you're willing to pay the price.