French VBCI sits at 9.7 with 30 mm + there are multiple with higher caliber (mainly CV90 family).
Yes, there are always many lightly armored targets at these brs, including MBTs, some you won’t be able to penetrate from the front (mostly Soviet with good armor), but you shred everything through sides in seconds and this is exactly what you will do most of time - flank and surprise attack. I should say that 9.3 became a very nice place since stuff like 2A4 was moved higher.
IFVs are overtiered in general, referring to the 9.0+ ones.
Cent 2 is my most used tank, It is basically invulnerable to Tiger 1 frontally in downtiers, can traverse maps quite easily and will pen near enough anything quite easy unless its a full uptier in which you become useless, 6.7 is its sweet spot. American Heavies are good at 6.7, would do just fine at 7.0.
I think you’re mistaking overtiering for BR compression. the tech difference from 6.7 to 8.7 is the most dramatic in the game making some extremely good lineups (like 7.7 britain) still be destroyed in uptiers because its tanks from the early 50s seeing stuff from the 60s and newer. Dont put them lower, spread them all out more
You didn’t really play with it. The issue is a mess to play with it if you’re not under 7.0 battle and of course, if decompression is getting fix, it would be ‘fine’ in 6.7
for now they are fine enough at that BR as any higher or lower they become OP or trash, with decompression of course the BR will change