I've had some great hatches in an LG 'bator. I used to have a still-air LG.
The best way to use an LG is to:
1. Put it in a room where the temp is fairly regular... no breezes, not near a heater, etc.
2. Get the temp set for about 24 hours before you put the eggs in
3. Once the temp is set... DO NOT TOUCH IT! The temp will drop slightly at times - usually at night and right after you add water. It's ok. Don't touch the dial unless temp goes OVER 103* and stays that way for more than 3 hours.
4. Get a thermometer/hygrometer and make sure they are calibrated correctly.
5. Add warm water through a straw or plastic tubing through the humidity holes. I used sponges cut into strips (to fit into the water troughs) to up the humidity at lockdown.
6. During lockdown... DON'T OPEN THE 'BATOR! If you do, your humidity will drop and you may "shrink-wrap" your hatching chicks!
I don't know if I was "lucky" or what, but I never had any big issues with my LG 'bator. It never held the same temp steady, but a degree or two fluctuation didn't seem to affect my hatches.
Good luck!