I think most of the rear-facing to booster type seats have quite a low rear-facing use, around 9kgs. That's the trouble with seats branded 'The only seat you'll ever need' The dedicated seats are usually a better seat for the stage they are designed for. It's hard to produce a seat that is excellent in all stages IYKWIM.
If you are after a seat for ERF I would recommend either the SnS Meridian or the InfaSecure Neon/Kompressor. They are tested rear-facing up to 15kgs and have the highest rear-facing height markers on the Australian market at the moment. But they are 0-4 seats. Infa have an 0-8 seat, but the rear-facing markers are quite low and I think it has only been tested to 9kgs for rear-facing.