I tried them like 23 years ago. Did notice a little gain of speed on the flats. Took time to get used to them. Heck, took me about 3 weeks to get used to them where I'd feel comfy staying down for a mile. After that it was easy so no problem after the learning process.
But once I started actually doing more demanding rides, they were a hinderance to my hand positions. More climbing rides, centuries with 10,000 ft types so I needed all the space on the hb's. The aero bars were just in the way.
My longest ride is 126 and never did I feel I was missing them or needed them.