So you get the 6+% rate for 6 months and then for the next 6 months your rate could be 2% and perhaos lower going forward.
Better to lock in a higher average rate elsewhere with CDs.

If rates go below 2% or so on the I Bond I plan to
sell my I Bond held after one year. I will have received the
9+ and 6+ rates making up for losing 3 months
worth of interest upon selling.