I ran a forte lunarlight 50gm tube on the front and a 120gm tube in the rear that a repair shop put on for me after a flat during a century. Had both for ~1000 miles, no flats in either one but I did notice that the light/thin tube would leak air a lot faster than the fat/heavy one.

I recently replaced both tubes with 70gm Forte ultralight vs lunarlight tubes and noticed that they both hold air almost as well as the super heavy 120gm tubes. I'd personally avoid paper thin 50gm tubes and stick with 70gm tubes - less risk of a pinch flat.