I have the National's and love them. No issues to date but have only had them for about 9 months.
JDUB NOTE THIS***** I purchased my Stage 2 and then purchased the springs a couple of months later like you are doing. I kept having issues with my bump shocks as it seemed that I was hitting them on every little bump. After several months, I figured it out.
The bump shocks come with a long profile impact pad if you specified you had factory springs when you ordered the shocks. When you install the aftermarket springs it will lower the back end of your truck and if you leave the regular impact pads on your bump shocks, you will hit your bump shocks on every little bump. They make a low profile impact pad for the shock that you should put on the bump shock when you go to the springs that lower the back end of the truck. If you order the bump shocks and springs at the same time, the shocks come with the low profile impact pads.
RPG was awesome and sent me a set of low profile impact pads for free once I figured it out and called them.