I recently bought a Frog 62 for my eight year old daughter. It is really great. Size wise it fits in between an Isla bike Beinn 24 and 26 and its weight is in the middle also. Price wise the Isla bikes are £400 whilst the Frog 62 was £270. You also get two sets of tyres one pair of hybrid which work really well off road and a set of MTB tyres and tubes both sets are Kenda. To be fair I think this is a bit of overkill as they are great value with one set of tyres. They also have some lightweight mudguards included in the price.
My daughter loves the bike and the weight saving over her old one is really noticeable off road.
The online reviews are all out of date so they have addressed things like small grips, cassette and they are now nearly 1kg lighter