I think there is data on H rods in the out years or past 10 years anyway. The T fusions are sailing along years out as a generality as far as I know though there are of course exceptions. Not so true for L fusions unfortunately.
I think H rods for T curves are a "solution" at this point to progression but Linda will correct me if that is not a good description of the state of affairs. And pedicle screws improve on H rods so I expect those are "solutions" for T curve also.
Not sure about the state of the art w.r.t. L curves. Hopefully pedicle screws will "solve" the problems seen with H rods.