My first time flying BA, I have WTP on a 772 4 class configuration (BA192 WTP is rows 21 to 25 2-4-2). I switched 22B to 21B (21A is empty atm). Currently only 1 seat in the middle 4 of rows 22-25 are taken (22D). Being 186cm, is 21B going to be comfortable for a 9 hour flight? Should i switch back to 22B, or one of the empty middles, or will those be filled in with upgrades at T-24?

Thanks!