This is exactly the issue i have, well had. Son is on the seatpost insertion limit of his frog 43 and i was keen to get him something light to keep his progress up.
Many options were out of stock (frog, isla, early rider) but then I looked at the Wiggins Chatres 16. Its on offer at halfords and with some discount codes i got it for 150, or half a early rider belter cost!
I also looked at the saracen mantra but it was still over 220.
Both quite light (not hoy under 6kg light) but still well under 6.5kg and the wiggins has a small q factor so easier to ride.
I am picking it up tomorrow 🙂
Cyclesprog.co.uk has a handy chart of most of the good kids bikes including all-important weights!