I have had ADS-B In for about 4 years (Stratus 2) and ADS-B Out for about 14 months (KT74 transponder tied to a 430W), and it's extremely helpful--it adds eyes and ears which help me "see" traffic that otherwise I might miss. With only ADS-B In, I only saw some of the traffic when I was flying in the Denver area (or other busy area with many ADS-B Out equipped aircraft). But there's a dramatic increase now, especially because so many are now having ADS-B Out installed in anticipation of the rush at avionics shops over the next couple of years.

A good "for instance" happened just this last Tuesday morning. I was moving my airplane from KGXY (Greeley) to KFNL (Fort Collins-Loveland) for some mechanical work. It's only 17 miles, so when people fly between the two, they mostly don't follow the hemispheric rule, because they don't fly high enough--KGXY is at 4700' MSL and KFNL is at 5,000' MSL. Nonetheless, I prefer to follow it anyway, so I'd climbed to 6,500' westbound. My ES transponder suddenly reacted and a voice said "traffic", and the traffic page showed on the 430W with a "spot" dead ahead (it doesn't show altitude). A second later, a voice from the iPad Mini 4 (Bluetoothed to my headset) said "traffic, 12 o'clock, 400 feet below". I glanced at the Mini 4, and a red window had popped up, which also said "traffic, 12 o'clock, 400 feet below". The map showed opposite direction traffic, complete with tail number, a mile away. I knew where to look, but I never saw the traffic. ​I wouldn't have even known about it, without ADS-B In and Out, since for such a short distance, I don't usually use Flight Following.

The benefits of ADS-B Out are available right now. It's not cheap, but IMHO, it's worth it, unless all one's flying is all in the pattern of a very definite rural airstrip.