I've been using only digital timers for the last five or six years. They bring their own issues. For one thing they're prone to burning out. When they do- it's not pretty. The time it happened to me I was away and hit home to a nasty surprise. The timer had melted, there was a big black streak up the wall and the ceiling was black above it. The grow absolutely reeked from burning plastic and the smoke in there must have been awful. I count myself lucky.
They're known to fail like this more easily than the mechanical ones. It's not a good experience
Buy high quality, and if you're running much power through it then make sure to read the fine print numbers on the package. Most will give a separate amperage rating for lighting- which is half the amperage it says on the front of the package.
Another problem with them is they can be very quirky when programming. It depends on the brand. When you program in a change to the schedule they often have a habit of getting confused and not turning off at the end of a lighting cycle. I had this happen many times and it's the reason I had to put in the indicator lights. I won't bother trying to explain alll the stupid programming quirks you might run into. Unfortunately some of you are probably going to find out.
