I'll throw out some obserations here which I'm sure will ruffle F/A-18 guys' feathers...
I've never met an 18 guy who would go low. Hell, I've rarely seen F/A-18 guys lower than 10k (I know they do it, I'm just saying what I've seen).
How low? I've flown in my helo at less than 100 feet and looked down at the top of an A-10 alongside of me. When they fly like that routinely, hearing this isn't that surprising.
And just for comparison, the only dudes I've flown in the Navy who have DFC's were on a flight where the crewchief shot five dudes out of a tree with the GAU-17.
100ft at tactical airspeeds requires 100% of your time dedicated to terrain clearance. Not to mention that there is nothing a Hornet guy can employ from that low.