My 250w SE bulbs are about 8.5 inches from the water. They are in DIY Lumenarcs. I use plastic chain to suspend the fixture from the ceiling. This allows for relatively simple height adjustment by using a different chain link in the ceiling hook to raise or lower the assembly. Just need to make sure the chain is robust enough to handle the weight and so far so good for me. Might be able to rig up something similar inside a hood with a shorter length of chain. May not be as elegant a solution as an elaborate sliding or even automated rig, but on the plus side, it's simple, inexpensive and easy to set up.
I only have a couple of small SPS frags at the moment, so can't really provide any useful info as to growth. What I have is doing well. Down the road I'll definitely be looking at LED lighting to replace the MH.