It would seem that the combination in the title would be extremely powerful, since you'd get at least 2 attacks (3 if Half-Orc with tusks) at full BAB all with full Sneak Attack damage. And if the DM lets your Master Chymist levels stack for purposes of calculating Sneak Attack like it would for Bombs, you're even better off. I know that the Cornugan Smash is better since it's a free action to Demoralize when using power attack, but I don't know if DMs would allow that. It seems extremely powerful.
Has anyone made a character like this? How did it work out?
Where's Vivisectionist?
The build is good... like any build with Shatter Defenses, a way to Demoralize enemies freely, and additional attacks/damage when they are Shaken.
One of those is a Monk with Medusa's Wrath.
Another is a Barbarian with Intimidating Glare and Terrifying Howl.
Or a thuggish Rogue with the Enforcer feat (APG).
If you use 3.5 material, Bloodsoaked Intimidate is fine too.
Or some monk/rogue hybrids.
The drawback is that it requires some investment, and it doesn't always work: some monsters are particularly resistant to fear.