Should I exchange VMFXX for VUSXX?

I've got about $100K in VMFXX right now because it's getting over 5%. I'm doing this instead of BND and such which have done nothing but lost money since I bought them over 3 years ago. So this is the conservative portion of my fund.

I read somewhere that VUSXX isn't taxable in California (but is federally taxable?).

If my math is right, with this data I've cobbled together

https://i.imgur.com/AuTpQ6d.png

I should save 0.37%... which I guess is about $370/year.

Does that sound right? Anything else I need to consider?