I am using a Quiet One 400, (1" in/out) on a manifold that services other items via ball valves with a SCWD that I drilled out & enlarged the intake & output's of the SCWD. The QO is submerged in the sump & has no problems, I also use a 1" union on the pump for maintainence. The SCWD has better flow now & continues to work well.
I have considered upgrading to a 600 pump & keep the 400 as a spare (Murphys Law)
I also use a QO 400 ona closed loop with another drilled SCWD
Since this picture I have added a 1" flap check valve below the SCWD on the main return from the sump ( top SCWD in pic)