FAR less instances of a grid heater issue. I’ve never known anyone to have an issue much less have to change one out. Glow plus are recommended every 100k, I’ve got 400k,375k,,265k,260k,250k respectively all around 30yrs old with original equipment. Those are what I own but have owned many others, family have owned a ton again without even changing one out.
Just changing a glow plug out can be a serious problem, usually seized in, sometimes just taking one out can break apart and fall into the engine. Powerstroke and Duramax both have very common catastrophic issues with them.
I like s*** that lasts. That’s why I buy what I buy. For me the glowplug vs. grid heater is like the inline-6 vs. v8 conversation, yes either can have a problem but one has drastically more at more repair cost.