You can only deposit 10k/yr but how does 9.62% sound?[0]
[0]https://treasurydirect.gov/indiv/products/prod_ibonds_glance...
[0]https://treasurydirect.gov/indiv/products/prod_ibonds_glance...
However, if one wants to hold a portion of bonds and a sub-portion of said bonds happen to be I-Bonds, then I see no issues with that.