Bertie is definitely an unsung hero of this site. Her knowledge and time spent helping people with car seat stuff is incredible and everything she says is totally accurate and well researched.
My 14mo has gone into my DD1's old seat, a Britax Maxway Plus 25kg seat which should last her until 6ish on her current centiles. Unfortunately DD1 is high centile in both height and weight and has just about reached the 25kg limit for the seats we have. I'd have bought a 36kg one if doing it again, knowing what I know now, but she's almost 5 now so we've moved her into a Britax Kidfix HBB. But pleased we managed RF till almost 5!