i've been messing around with my suppanomimi for about 30 minutes, wearing it, taking it off, and judging the TP reduction
Maneater/Seiryu's Sword
Without Suppa:
Every round of attacks returns 12% TP
With Suppa:
I get two different amounts of TP per attack round, 11% & 12%. Each round of attacks goes back and forth between 11%, and 12%, which leads me to conclude that with this weapon setup, I'm losing 1% TP every other round of attacks (or .5% lost per attack round)
being the max TP% per attack round (pre-suppa) was 12%, this means I'm losing 4.16% of my TP per attack round (correct my math if wrong, plz)
however, being that Suppanomimi reduces Delay (When Dual-wielding) by 5%,
my attack speed increases by 5%, but TP gain decreases by 4.16%, giving the slight edge to Suppanomimi
(edit: Suppanomimi Dual Wield Delay information can be found
here)