I have had the Caldwell chrono for about 3 weeks. I have used it twice.
IU have connected it to both my Iphone and my Samsung Android.
The Iphone app is very nice, needs some more fine tuning to get complete info, but is heads above the Android version, which truly sucks.
The Chrono by itself only records one shot at a time, the app allows you to gather info for multiple shots attached to the same reloading data. Allows for templates that can be pulled in, and data unique to each load can be added.
As far as I know, it is the only Chrono that communicates with a current electronic device. I believe there is at least one, if not 2 others that require an RS232(?) interface to a laptop.
Problems I have had.
1. Shooting underneath a roof, but some mist got on one sensor, and it wouldn't function properly.
2. 3ft from pistol to Chrono did not work at all for Bullseye and Autocomp. Worked fine for Titegroup and CSB1. Moving the Chrono to 6 ft solved this problem.
Based on the cost of the Caldwell version, and the cost and functionality of the competition, I would definitely purchase again.