This is how I have top roped solo for many years using the Petzl Shunt. There are many different devices on the market and ALL of them have pro's and con's. They all pretty much do the same thing, so I have stuck with the Shunt since I have used it for over a decade without any serious incidents.
Ultimately, no device is infallible and all have a risk of failure. The most important thing is how to use your chosen device correctly! Any style of climbing is dangerous and we should all approach it with this knowledge in mind.
There is also an excellent video by pro climber Dave MacLeod on using the shunt. I advise you watch this too:
https://www.youtube.com/watch?v=q4N2WGcABLo
00:00 Start.
00:36 The Petzl Shunt.
01:11 The Set Up.
02:18 Attach the Device.
03:09 Using a Chest Harness.
03:44 Test Your Set Up.
04:49 Disclaimer.
05:03 End Titles.
Music by Bensound
Artist: Benjamin Tissot
License code: VGRHORAB5LCUJMWR