That's a really good price for a SS AW5. I paid a lot more than that for mine.
When you buy 'stuff', do you go for practical or do you prefer spending a bit more for the precision / finer things? It's really about who you are. It seems to me that your having chosen to spend a bit more for the the stainless watch, you're probably in the second category.
Ruggedness wise, I think the sapphire crystal will be much less likely to scratch (that's why they put sapphire over the iPhone's camera lenses). My SS AW5 still looks great and it still looks new. but then again, when you buy the more expensive item, at least subconsciously, you tend to take really good care of it.
Your call.