We have several Graco Slim Fit convertibles that we use in harnessed booster mode and they are great and nice and light (although I think the Maestro might be lighter). It’s more plush than the Maestro, if that’s important to you. I believe it is nearly the same seat as the Graco Tranzitions/Wayz harnessed booster but I had difficulty installing that one, which seems to be a known issue for some cars. It’s less expensive than the Slim Fit though.
Mom to a spirited, red-headed, former 28-weeker 10/2009 and a more mellow monkey 12/2013.