I just finished installing both yesterday on my 1987 300TD. I had a horrible ride, any bump would send me bouncing into the headliner for quite some time. The new accumulators have cleared this problem up completely. It handles like a different automobile, smooth over even very rough roads.
From my research (I am definitely not an expert), it appears that adjusting ride hight with the control valve does nothing to "activate" the SLS. It is a system that is always working. There are no traditional shock absorbers or struts. There is always hydraulic fluid moving in and out of the strut, the control valve simply changes the amount locked in the system. This post made sense to me...not sure if it will to anyone else.