Whoa! That is awesome that EVOLV kept it the same dimensions as the DNA20!
Part of me thinks its excessive, but there has been times with my dual coil RBA that I would have liked to go over 20 watts and still have it fully regulated.
In all reality though, all you need to do to get over 20 watts on the DNA20 is put something under 1 ohm, and drop the wattage on the DNA20 below what it can regulate, then the DNA20 just sends the full battery power through to the 510, which can be over 20 watts depending on the resistance of the atty.
The benefit of using the DNA30 to get over 20 watts is that it is still fully regulated, and you could still fine tune your actual output power.
IME running the DNA20 at full 20 watts drains even a 2900 mah cell quite fast, seems to me faster then the same cell in a mech, the regulation has some overhead and consumes additional power.
I am really curious if the DNA30 is perhaps more efficient in the 7 to 20 watt range then the DNA20 is, it is conceivable that the DNA30 would be more efficient and might give better run time.