Supplement or replace flat with inclines?

In the 5x5 program, Friday's format give you the option to use an incline instead of flat. And in the DFHT program, one upper body day also gives the option for inclines.

So if you're wanting to simply replace the flat bench with inclines, I see no reason not to. If you're wanting to add some sets of incline in addition to your 5 sets of flat bench, I'd say no.