Right off the bat: 2015 Fit Ex with the Manual Transmission and 115k+ miles.
I started smelling fuel in the cab last week and finally found the high pressure fuel pump spraying under its foam cover from a split in the plastic section...

I should have all the tools I need to swap in a new one, and with shop markup and labor on a ~$400 part, if it's reasonable to do so, I'd prefer to.

Reasonable idea, or are there any issues I could easily miss that aren't coming to mind which would justify taking it to a professional?

 

Go for it, absolutely.

Keep the internal of your female fittings clean; external of male. Vacuum if you think you got dirt in one or the other.
IPA is the only non residue leaving solvent...
Get nice and snug on the lines. You'll be alright.

DIY is always worth it. Just bought a VR for my second used alternator. Looking to keep them in service as long as possible with $350+ for a new unit... No thanks.

Good luck to ya.