From a developer perspective is secure boot more of a obstacle than really useful. You need to use gummiboot, etc. to terminate the signing in order to use developer kernels without having a bottleneck, that one person in the company that does the signing, in the development process. (I am currently working with an Intel Quark X1020 where secure boot is enforced, it's not really nice)

U-boot is ported and regularly run on the MinnowBoard with an Intel Atom.

Do you speak about tianocore? I don't have much experience with it, can you configure it as well as u-boot and just compile in stuff you need?

Update: If you didn't know, u-boot supports signed images too. So UEFI is not necessary for this.