The bigger the gap between wall and TV, the bigger the spread of light across the wall will be. A 3cm gap is fairly common (for LCDs at least), as that's the depth of a typical (non-slimline) bracket.
The new Phillips Hue gradient lightstrip should be more effective than a standard lightstrip because it's angled to project the light at 45 degrees, rather than directly backwards like a normal, flat lightstrip would.
How far would a lightstrip end up from the edge of your TV ? Lightstrips tend to have a minimum bend radius that could make things tricky for you if the distance isn't big enough.
Just be aware the new gradient lightstrip requires the Hue Play HDMI Sync Box to work properly so not only does that add £230 to the cost, but it also means it'll only work as intended with external sources and not the TV's own apps or Freeview tuner.
I'm not sure how the gradient strip will work without the sync box. I suspect it will just display solid blocks of colour like the normal lightstrip, but I've yet to see confirmation of this.