Lighter tuners move the area of reduced sustain (every neck has one or more, some are just more obvious than others) up towards the bridge, but a couple frets at most - in most cases. That sometimes makes things worse, but usually it's better if you go all the way to really light tuners (the 40 gram-ish ones).
I have roasted maple necks (roasted maple is stiffer than normal maple, and also lighter). Both of those things move the AORS (yes I'm acronyming Area of reduced sustain) up towards the bridge a bit. My necks are 5 string necks (bigger cross section, that also stiffens things_. They have graphite reinforcing rods (yet more stiff ness). They have Hipshot ultralite tuners (a neck is what we Physicists call a mass loaded bar, and reducing the mass moves the resonance upwards in frequency). So, 5 things in my necks are different than a stock fender 4 string neck, and they are all working to move the resonance upward. Net result is that the AORS is at the 8th or 9th fret, rather than the 5th or 6th - up about 3 frets. My necks don't have what most folks would call dead spots, but if you go looking for the AORS, it's there (as it is in all necks), it's just not obvious - you have to know what to listen for. I have one neck which has a roasted maple fretboard, and it's a really tough AORS to detect.
I would say go for lighter tuners. Even if it isn't drastically different AORS/dead spot wise, the better balance and half pound less weight is something you will notice.