If you feel you need to get your speakers out into the room more for them to disappear, and you can't do that with the Thiels, you might be disappointed looking at Omni-directional speakers. Every Omni speaker I've heard does best well out into the room where their 360 degree dispersion creates the 3D effect they are known for.
Do you have the Thiels facing straight forward or are you toeing them in? Have you experimented with this aspect? That is often a variable to achieve the disappearing act.
I still have Thiel CS3s now doing HT duty, but as good as they sounded when I used them for 2 channel, disappearing wasn't a strong suit. Maybe my setup wasn't optimal either.