It does work, and no downside. If you want damage that is.
A lot of people do not realize or refuse to believe is that there are different base damage values to Human, Nova and Dwarf attacks.
Nova form attacks have high base values
Human form attacks have medium base values
Dwarf form attacks have low base values
And lastly, if the attacks are similar in name and function, they can still be vastly different. Warshades Cone Attacks are a prime example of this. Nova has high damage, no knockback, no stun. Human has low damage, high chance for knockback, and stun. Your extracted essence's cone is also similar in name, but is all damage like Nova's
What does this mean?
Your Human Form Solar Flare will always hit harder than Dwarf Solar Flare
And your Nova Detonation will always hit harder than Human Detonation
From my own personal experience with both my first set of khelds I went above and beyond for their builds. Even as low as level 15 I can cycle Nova Eye and Nova Blast. Nova bolt is a mule. And that was by accident.
I am Nova form most of the time. Human form is for utility and some nukes/aoes.