I had a guiche for about 18 years... like my other piercings, it was self done, and I have to say it was the most difficult one to pull off solo... Just no way to get a good look and both hands in the right spot down there...
It was more problematic with care, partly due to location, and partly due to accessibility... but once it healed it was fine.
The most important aspect of the guiche is gauge... you want a fairly robust gauge, nothing finer than 10... 6 is more ideal... the larger gauge offers less discomfort and less like to tear or migrate out, But there is a limit... sizes above 4 can pull continuously and are likely to migrate out unless you get a very thick pinch of skin to pierce.
Multiple Guiches in a row actually change the shape of the perineum into more of a flap of skin and are really very stable, much moreso than most surface piercings.
I wore a ring with a captive rod... with a small stainless steel chain looping from the ring ( either end had a loop that the ring passed thru ) When lying on my back, the chain dangled down to provide anal stimulation during sex or masturbation...
Initially, I had a small stainless weight on the chain that I really loved for its stimulation... but it kept getting pulled on during daily living in ways that were kinda painful... so I simply opted for a slightly heavier, flat link chain, and that worked great. ( flat link chain is like the kind of chain you see on a dog's choker collar...the links are twisted to lie flat... this style of chain slides better and is less likely to get caught, and comes in very small size links suitable to use in body mods.
In 18 years I never took it out...
But I do have to concur with Riven in the fact that they can be quite uncomfortable from time to time, especially if you spend a lot of time doing something like driving. ( the combination of sitting, AND moving your legs to work pedals just really tends to twist the little bastard in ways that
Once I hit my 50s, the guiche became more troublesome... I was driving a lot more and the discomfort was getting more noticeable, and the woman I am seeing was not into piercings, so I took it out.
However... the 18 years I had it I never regretted having it... It gave me a lot of pleasure in its time... and then, in the way of all things, passed .