You need to be clear on precisely which unit you're looking at. If it's the v2 wifi, that's 900 watts. The v1 wifi and Bluetooth models, on the other hand, were 800 watts.
You save money by buying the Bluetooth version currently (methinks Anova purchased too many of the Bluetooth system boards...so that's why it's still available) - but you need to understand that the bluetooth-only version may not support the upcoming feature set promised for the ANova Nano as well as the Wifi PC. Multiple device support as well as staged cooking support are two features that most users want (the other highest rated being the ice bath feature).
Heh...also have to ask - why would you have wifi / bluetooth issues where you live? Are you in some 2.4GHz spectrum maelstrom around your house? Heh. Or do you live too close to a transformer station? (seen that a couple decades ago when I was in support at IBM).
800watts is fine for most purposes (I have a v1 wifi unit that I'm very satisfied with). If you're planning on doing a tailgate party for several hundred people, you might need a few more units.
Most of us just set the units manually (I'm a big fan of scheduling my cooks in my calendar, so it's sync'd across all of my devices). The wifi units have the added benefit of being able to check on the status anywhere, so long as you have a data connection to the internet.