Ah, okay.
Yeah, the LS3/5a -- although two-way, and not concentric -- was pretty fabulous for near-field listening, largely because that's what they were designed for. I'd lean towards the LS50 just for that reason. I imagine (straightens throat) the imaging would be pretty superior on those. Bookshelf speakers aren't necessarily designed for nearfield listening. So...not quite common knowledge, but it's probably a statistically accurate generalization.
I'd be less concerned about the port. The biggest concern with having it close to the wall is that any chuffing might get exaggerated, and I've never been able to hear any on any speaker.