As far as engine mounts go... I've gone from leaky OEM mounts, to Poly (banzai) mounts, then switched from poly mounts to solid mounts, and finally went back to (great condition) stock mounts.
If you're maintaining the stock mount design (metal arm with soft dampening around a metal connection bolted directly to the subframe) then I would agree that $420 is a bit extravagant since all you're doing is drilling a hole through some poly and bolting it in place. In this configuration it's a see-saw balancing act of stiffness/shifter feel and vibration transmitted to the body.
The mount that FFE recently released is different from the tradition engine mounts which reuse the stock (steel) arms. The FFE setup basically has a bushing mounted into the arm with the connecting bolt mounted horizontally to a cup (as opposed to the vertical connection directly mounting the arm to the subframe). This allows for a more solid feel while greatly reducing the vibrations transmitted from the engine to the body.
Call me a fan boy if you want, but personally I find the perks of a more civil cabin, while maintaining the better mount, to be worth the money. Plus, I like to support the small businesses that support our community.
If I wanted to stick with the traditional engine mount design than I would just reuse the pair of great condition OEM mounts I've got currently..