Mine cost a quarter of the app-based devices I've seen and the one difference is that I have to take a glance at a little table. I don't mind that. And whether

Mine cost a quarter of the app-based devices I've seen and the one difference is that I have to take a glance at a little table. I don't mind that. And whether a device has controls doesn't matter with regards to hot water contact. It has to be properly sealed either way and capacitive buttons work fine for this (not worse than the low-quality buttons they'd use otherwise). The main feature you get with Bluetooth is another point of failure thanks to connection problems, at least that's my average experience with BT.