The LV5 Infermon from BT2 helps to reduce 1 evolution cost to LV6 Diaboromon and the new Infermon from BT5 can evolve from LV3 Keramon with 4 cost (save 1 cost if we bypass LV4), its inheritable effect is also very valuable: When this digimon get destroyed, it can spawn 1 LV6 digimon, 3000DP, white color and if we have BT5 Kurisarimon inheritable effect to use, this token can attack in this turn as well.
Compared to Diaboromon from BT2 (BT2-082), the new BT5 Diaboromon is cheaper to digivolve, and immediately spawn a token diaboro when digivolving. This digimon is maybe a preferable to move up to LV7 Armageddemon after his digivolving since there is no more benefits of him. For the Diaboromon from BT1, It is best if we can digivolve into him and use him to attack at the same turn, so memory will need to be considered here.