Healy,
As you said, you had holes from scraping the road. Scrape the road a few times with a cast alluminum sump and you'll have much worse. You'll have cracks or breakage, which may or may not be repairable. I think aluminum sumps are really neat, but they belong out of harm's way, like on a high ground clearance saloon or on a show car, or perhaps on a race car, if their protection can be assured. It's a question of economic practicality to me. Enjoy.
Motorbill
From Lola to Land Rover, If it's British and has wheels, it's likely I've bloodied me knuckles thereupon