I second that.
Printable View
When I went from TH8 to TH9, I had max defs/troops (except some of the dark ones), lvl 8 BK, all lvl 7 walls and about 15-20 skulls on getting to TH 9.
As I say whenever this question is asked. I got better loot at Th9 than TH8. But, it was under the old loot system.
The theory on maxing comes largely from the existence of the loot penalty. I found the benefit being given by stronger/more troops completely outweighed this. Also, since then, the loot bonus on attacking higher TH's has been removed.
On maxing walls, I would say that 30m spent on two lvl 3 xbows does more to improve the defence of your base than 60 skull walls. This is also an important factor now for clan wars.
For me, maxing is more about ideology than something really needed to compete in the game.
Having said that I would also advise levelling up a few more defences before you go. high lvl teslas are great. That extra lvl on archer towers is worth a lot too.
Max TH8 I regret not doing it, TH9 loot stinks for me right now and I feel like moving straight to TH10.
Definitely not, I think th8 is the most important to max out. You're giving up easy loot if you don't and you're going to have a lot of new expenses with xbows and walls at th9.