Bud, I think the fact the S5's are a sealed box does make them easier to place. Certainly review commentary suggests they are easier to place than many other speakers such as the Wilson Alexia's. I have a challenging room as the area behind my speakers is not even, so in my situation it was an important consideration to have speakers which were non-critical with placement. I took some measurements of the distance behind my speakers. There is 450mm to the hot water cupboard behind my LH speaker, whilst there is 280mm to the diagonal steel support beam behind my RH speaker, otherwise 1170mm to the rear wall. I have my S5's placed along the long wall in a near field listening position as per the
Cardas Room Setup Guide. With my open hardwood stairs & atrium, somehow it all works well. But I think the S5's non-critical nature helps. The Cardas Setup guide is a good starting point, but if you have a bit more freedom you could get your room professionally measured to guide to you find the best room placement for both your speakers and listening position. I have less options, so I focused more on getting the distances right between my speakers in relation to the listening position. I attached a couple of photos of my room showing the speaker positioning.
Cheers,