I teach high school, 11th grade AP English Language and an SAT prep class. We just implemented a Bring Your Own Technology (BYOT) policy last month. My boys are in a different district, and have had the policy all year. My youngest is in the 3rd grade, and most parents don't send their children to school with technology. Most teachers in his school don't have the students use the technology other than in computer class anyway, and there computers are provided.
My oldest is in the 9th grade, and they can BYOT, but the school district provides iPads for every student, so they just take those to school. It's the first year they've done this, so there is a learning curve for everyone. My son says that a couple of the teachers really use them well for teaching, but most of them don't use them at all. He also says that many students spend a ton of time playing games on them. Of course, students are excellent at pretending to work on the iPads, but actually be playing. When my son has used his iPad at school, he has completed some really cool projects, and it has allowed him to streamline his notes very well, too.
I have (dare I say it!) broken the rules in the past and allowed my AP students to bring in technology. Now it's allowed anyway. It's really not a problem if they have different devices, or if I don't know how to use them. I allow technology for projects we are doing, and usually it's for group projects. I'll simply let them know a day in advance that they can bring technology the next class, and introduce the project so that they will know what kind of technology would be beneficial (powerpoint, moviemaker, filming of some kind, etc.). Then the next day they come in and work. I bring in school laptops for those who don't have their own devices, so everyone has what they need. It's just easier to save their work if they have their own devices, and usually their own devices work better. Ours are ancient.
As for elementary, though, no. We don't send technology with our 3rd grader, but if others choose to, that's their decision.