I agree with BoomerD on this one. I use those exact timers, and have been for about 2 years. The only time that they have shifted on their own so that the timing was off was when we lost power for about 15 minutes, but all 3 of them stayed in sequence with eachother still.
The only thing I will use digital timers for is the mixing pump on my kalk reactor, because I need it down to 2 minute incraments.
I have had problems with digital timers shorting from getting wet (nerite snails like to crawl out), knocking an open faced analog out of time, and lower amperage cheap timers sticking in the "on" position with the 250w MH that I used to have. The timers that BoomerD linked to fixed all those problems for me.