I've tried a number of types since changing lights Mark.
I started with the HPM heavy duty ones, manual but rated to 2400W, and within a couple of days they failed and wouldn't turn my lights off.
Bought cheapie digital timers, still rated to 1200W, and 1 of these failed and again wouldn't turn the light off. Replaced this one with a simple pin type job I had lying around and all have gone fine for several months.
In other words the HPM heavy duty are no better than any other timers, and I've now got 3 that may be buggered and it's a waste of $29.95 each, compared to the $9.95 jobbies I'm using a present.
I will definitely be going to a timer tripped relay like Chimera on my next tank.