Are knobs small on the 8.1 gear ratio or the same as the American version? 

The difference is in the handle length "as far as I know". Knobs may be different too. Try the search function I think this has been discussed before with more knowledgeable replies then mine.

FM

20-23 JDM Metanium including 24 DC always uses this type of Knobs and handle lengths are typically shorter.

6 & 7 speed = 84MM handle

8 speed = 90MM handle

'20 = 70 size spool

'22 = 30 size spool

'23 = 100 size spool

 

 

2020 USDM uses this type of knobs and handle lengths are a little bit longer.

6 & 7 speed = 90MM handle

8 speed = 96MM handle

'20 = 150 size spool

 

 

24 USDM/JDM Metanium DC are identical.

6 & 7 speed = 84MM

8 speed = 90MM

Spool = 70 size

 

 

They basically bantamized the met for the US market with bigger knobs and a deeper spool.  In Japan the two being distinctly different makes sense with the bantam being the higher capacity aluminum frame HD reel with big knobs and the met being more of a precision instrument with thinner knobs for more feel.  Knowing the US market would complain endlessly about thin knobs and too little line capacity they made the bantam and bantam light weight.