To put some objective numbers to the claim I will compare Phoebe vs Rath vs Pendles damage output. Note: I only have the mutations unlocked for Phoebe, so I might be missing obvious changes, and I am using the data from battleborn bible and command screen information, so the damage might be off if they scale oddly as they level up.
Base Attack DPS:
Phoebe: 192
Rath: 198
Pendles: 172
Base +Helix boosts to base attack:
Phoebe (3R,7R) : 1921.181.2 = 272
Rath (7R): 1981.18 = 234
Pendles (3R): 1721.25 = 215 (only from behind)
Base + Helix boosts to base attack + Ult + Injection spam (pendles):
Phoebe: 439 DPS over 5 seconds, 356 over 10 seconds
Rath: 415 DPS over 4 seconds, 306 over 10 seconds
Pendles: 300 dps over 10 seconds (Assuming he can apply injection 3 times, and that it doesn’t interrupt his baseline DPS)
Now obviously this is a gross simplification, I have left out lots of synergies, Helix choices, and gear sets and other factors that would need to be taken into account to give a real DPS comparison, but I think the trend is easy enough to see.
Made me chuckle since I saw a rage-post yesterday about how freakin fast he is^^ Its interesting how the perceptions of his speed differ so far.