menuki
500+ Head-Fier
Ha, ha, ha... I admire your distinguished HeadFi panache.
To be honest - my initial order was T8U, but audio-greed and double twin 33AP Sonion curiosity made me upgrade my order to T12U... therefore I can relate in a way with your latest impulse.
Remember - it is most probable that your T8 will better your B8, but it is also likely that you would still not be wowed at first listen. Just do not hate them when they reveal that your most beloved "fun" IEM was shamelessly cheating on you from the start.
That is actually what I struggle with as well! Phew, not alone. Anyway, I don't know if the T12U would sound that much than the T8+U. I asked Gareth himself and will wait for his response.