I am just looking back at my state savings and have a few hundred k in issues 6, 7 and 8 of the 10 year bond. Some of the later purchases, in particular issue 7, would be worth getting repaid early to invest in the new issue. It would be a pain though plus I presume that unless is possible to seamlessly reinvest, any money invested would be regarded as new funds and subject to the 120k maximum holding limit.
issue 6 - 16% total return
issue 7 - 10% total return
issue 8 - 16% total return
issue 9 (from 1st October 2023) - 22% total return