Looking for any new owners of the Soundbar 500 or 700 model or even the Soundtouch 300 (as is has similar specs without the voice assistant) on whether they think it would be a worthy upgrade from the Solo 15 II. I would likely get the corresponding Bass Module to add the bass and am just looking for any input from owners of the newer soundbar products.
The Soundbar 700 and SoundTouch 300 would be a major upgrade especially with the bass module added to them. Biggest reason being there are more speakers built in so you are going to get a much better home theater experience. Also the Bose phase guides built into those two soundbars will give a much wider sound stage and will actually use reflections in the room to provide you audio where there are no speakers.
The Soundbar 500 is a great soundbar as well, but between the Solo 15 II, there won't be a huge difference between the two. I would recommend checking the new soundbars out at a local store to give them a side by side comparison.