The tack/gybe function is something I find useful on long windward/leeward courses where you can not see the marks after rounding. I.e. the old Tornado courses.
What we do, is we round the mark, and then note how many minutes we sail before we gybe, and how long we sail between gybes. That way we have better control on where we are on the course, and we know how much longer we have gone left/right on the course compared to the previous lap. I dont know what kind of screen and other hardware you want to run and what is needed to visualize this. It might also be just me who thinks this is good to have and like to structure my sailing like this. It is your watch
I dont think it is against any current class rules to have this functionality, but there might be some classes who dont allow this.