Checked on my usage of the term 'Brittle' regarding sheet stainless and yes, I was wrong.
Even so, that does not change my preference for using 7075 T-6, or, T-651 for a ride plate given its tensile strength is within 2.35 percent of 303 SS and its density is 65 percent less than that of stainless. Also, there is the 'workability' factor ... as Mark has pointed out SS is much harded to cut, drill, etc. than is any alloyed Al.