I only use my gralab 300 on my older 4x5 durst as exposures are long enough not to worry about variation of second timing. The gralab is not very accurate when setting exposures that are short. Same with time-o-lites, not very accurate. They are popular because they are simple and affordable but not the best choice if you have a little bit of a budget to spend. On my main lpl 670 i use a gralab 450 with footswitch. Very slim machine i have wall mounted behind the enlarger. Dials as i dont like the button time setting design versions of the more advanced gralabs. Dial setting is also very fast. Metronome when counting down, great for dodge & burning and 0.1 second timing, which is really needed for small prints with the head low.
I never connect the timers to a safelight as i use a thomas duplex, i just dim the vanes if i know im going to be working for a bit of time with lots of paper out, such as cutting from long rolls. If it turns off it needs to warm up again before its safe to use.