Going to an eheim would be a serious downgrade in terms of quality and reliability. I would also plan for about 1/2 the actual flow of the "rating" under any sort of pressure use. If you have 11' of head (alot!) you should stay with the iwaki or maybe get a smaller pan world that's still designed to work in pressure situations.

Another thing is that eheims are tough to hard-plumb; if you remove the hose barb, the fittings are not tapered threads, but straight threads sealed with an o ring. Good luck trying to get that sealed with a taped PVC fitting in 11' of head pressure! If you want to use the hose barb and flex tubing, it's not an issue.