Is a higher SPF mineral sunscreen worth it?

SPF 30 blocks roughly 97% of UVB and SPF 50 about 98%, so the incremental protection above SPF 30 is modest if you apply enough and reapply. The SPF 50+ and SPF 70 options here (Blue Lizard, EltaMD UV Sheer, Neutrogena) offer a buffer for incomplete application, but adequate quantity and reapplication matter more than the number on the tube.