Typically an add a leaf will provide you a gain of 1.5" - 2". These additional springs help to reclaim arch in the springs. Most of the time these are sold for spring repair.
If you are wanting some minor lift there is nothing wrong with add a leafs springs. I recently installed a set on a 98 Chevrolet 4wd Scottsdale truck. They gave the truck about 1.5" lift and the owner was pleased with the "new" stance of the truck. I also installed new shocks, steering damper, and a set of 32" BFG AT Radials on the truck at this time.
All said and done the truck looked GREAT and road / drove just fine. It did ride a little stiffer but nothing bad by any means. Although, I am in no way saying that the short wheelbase of a Sammy will ride as nice in comparison. My guess is it won't be much worse than any other lift but will still be a noticable difference.