If I weren't so lazy I'd do a head-to-head comparison of my SVS PC-2000 Pro vs Rythmik F12 as the prices are comparable. Right now they're in two completely different rooms (open living room / kitchen versus dedicated HT) so it's not a fair comparison.
Altogether seemed pretty close so price and form vs function would come into play.
1. The bluetooth app is nice on the SVS
2. The SVS is the more attractive big black box so if it were going in a multi purpose room it would get the nod
3. In a dedicated home theater where it is really dark most of the time, I might choose the Monolith
One annoying thing about the SVS app. I have my PC-2000 Pro in standby mode so it should turn on when it receives a signal. The app doesn't actually tell you if it's powered on. Seems like an on/standby indicator would be a pretty easy thing to add to the home screen...
Chuck, write them a letter! I wrote to Amazoid a couple years ago and suggested, "Gee, it'd be cool if Alexa could play nature sounds to fall asleep to," they emailed me back and said good idea, we're looking into it, and it appeared a couple months later.