So heyyyyy how about some more monsters.
Vermin lords feel a bit weird to me. Their CR (17) and description implies that they're to be used as high-level BBEGs, or at the very least lieutenants, but their skillset and general ecological role feel far more typical of a mid-level creature to me. You can argue a lot about at what level big bulky vermin stop posing a threat to PCs, but it's generally agreed upon that it happens before casters get 9th-level spells.
As for their actual viability as PCs... not good. 25 monstrous humanoid HD are a heavy burden, and with pathetic stats (the highest is 22 constitution on what I repeat is a 25 HD monster), weak SLAs (the strongest is Creeping Doom, of all things), and general underwhelming abilities (Uncanny Dodge, Regeneration, Evasion and Poison are all nifty, but ridiculously weak for an epic-level PC.
The vermin lord has enough trouble threatening level 17 PCs: whether it's a fair match for CR 25 monsters should be obvious. -0 LA, just play one of the vermin-themed monsters with less RHD.