Tonzz I used it exactly the same as you intend to use it and have had no problems in over 2 years so it's not a major worry.
It works very well above the pump I just lift the pump up to clean and give it a good hose and then drop it back in position. I can lift the pump clear of the sump and hose any rubbish off without anything going back into the sump so it's a winner there.
Bacteria builds up on the outside of the hose where it sits in the water and that's probably a plus, but if I were to redo anything I wouldn't use it again except too be able to lift the pump out, it hasn't cause me any problems whatsoever but I would try something else if there is a next time.
Your idea of using it for the pump and then using PVC would be the ideal way too go.
