Maidstone is not as great for commuting but have you checked the high speed out of Maidstone W? Expensive but worth checking.
Valley catchment is tiny. Really tiny. Amazing school. Less amazing housing stock. But good for your Petts W £.
Bexley is just as bad as Tonbridge if you don't pass - bad as in everyone hates the comps but really ? Come on be realistic. If they just miss Grammar and you keep them on the straight and narrow, they will be fine.
I would rather mine were in a Kent comp than Kemnal. If that's your dilemma then I see where you are coming from. Beaverwood doesn't bother me so much.
What are your Bromley catchment schools?
Do you reach Crown Woods or Coopers?
Cleeve Park is hugely on the up. Does it have sibling link for the younger ones if the older gets in? I haven't looked.
If you want to move for better schools then go to Blendon, Bexley. Hurstmere, Blackfen Girls both have academy links with Sherwood Park primary (yes it's been failing but I predict a swarm for that academy link) and you're still close enough for both Bexley and Kent 11+
I grew up in Kent.
And Mascalls is a great school so otherwise, move to Paddock W.