TH9 - No.
If I build a strong army and use 4 spells I can get past them. If I take a light farming army (usually I use BAM) I can't. In my view this is the right balance. I shouldn't be able to roll over a TH above me with a light army, but I should be able to have a good fight if I'm prepared to invest in a strong army.
I do take the point on TH10's with disco's and weaker other defences being tougher than a max TH9, but, I don't see why this is necessarily wrong. If it is wrong then where should the balance be? by way of illustration, I have 1 AT and 1 AD to do before I max TH9 (well max defence, my walls/heros are pretty rubbish) and if I went to TH10 before doing these two buildings and got two ITs, my base would have stronger defences than a max TH9 and I think that is right. So how low should defs be before it is wrong for a base with those low defs and two discos to be tougher than a max TH9?
Each of us can go to TH10 and get them if we want.

