My take on the RSK or not, is that it depends on the springs to be used:
1) A spring that at ride height remains positively-arched (like the rears are) under compression will move the axle forward if in factory configuration, while the force of impact is trying to push it backwards - the two "collide" and the suspension ends up fighting itself and giving a lousy ride. Doing an RSK affixes the front of the springs and allows the axle to move backwards under compression, which is also the direction the road force is pushing it into, so the suspension soaks up the bumps better.
2) A spring that at ride height sits flat or is negatively arched (F250 front springs for example) with factory bracketry upon compression will want to move the axle backwards slightly, which is the way the road force is pushing it. If you do an RSK on one of those and affix the front end of the springs and let the rear float on the shackles, the spring will end up trying to pull the axle forward while the road force is pushing it backwards, and you'll probably end up with no better ride than before.
I'm using big block gasser springs under my IDI, they must be somewhat softer than diesel specific springs and end up with a slight negative arch to them at ride height (which heights is about and inch lower than factory 4x4 F350, but for my purposes that's actually a good thing). Because of this I kept the factory setup of fixed rear ends of the springs and shackled fronts, I also angled my shock towers back some 10-15 degrees so they absorb road force better. Overall I think my setup rides about as nice a my 2wd front did, which was actually quite nice to begin with. If I were going for a lift and/or positively arched springs I'd do an RSK in a heartbeat, but for the spring geometry I'm running this setup works out quite well.
About the frame alignment pins, I've also smacked my head on them a few times, every time it happened I thought of chopping them, sure glad now I never followed thru with that