[noggin]

TV displays [3D][1080p@24Hz]
Picture looks good, the same as with hardware option, not different that I can see.
No stutters, smooth image.

But isn't that half the resolution of "Hardware Based"? So there is a "big" (?) difference and you just can't see it?

AIUI it isn't 'interlaced' in the way 'interlaced' 3D is usually thought of. This isn't a 1080i signal carrying 2 x 1920x540 eye feeds in consecutive fields (which are effectively sent sequentially over HDMI as 'real' interlaced video is) - where the vertical resolution of the 2 x 1920x1080 eye feeds is halved. The 3D TV receiving this signal doesn't deinterlace it as it would conventional interlaced video (merging fields with static content, and interpolating fields on moving content) and instead treats them as two 3D eye feeds, scaling the 2 x 1920x540 fields back to 1920x1080 fields, and then treating them as if they were alternativing frames for each eye. (Totally ignoring the real reason for interlacing). This requires that the 3D TV is fully aware that the signal is 3D interlaced as it handles it very differently to 2D interlaced content in the same 1080i structure.

AIUI Instead of doing this it is potentially possible to use a similar, but subtly different, technique - using interleaving - so 2 x 1920x1080 eye feeds are scaled to 3840x1080 and merged to create a 2160 line image? So no vertical resolution drop. The Passive polarising filters on the 2160 line panel are configured so that 1080 lines are polarised to go one way, and 1080 lines are polarised to go the other way, in an alternating fashion. (You wouldn't want to encode a video in this format - as any compression artefacts could involve eyes 'leaking' - which is why TAB and SBS are used in preference as storage when MVC can't be - but as a baseband uncompressed interconnect it makes sense)

In baseband video terms the signal isn't interlaced, it's a progressive 2160/24p signal that just happens to have 1080 lines from one eye, and 1080 lines from another eye interleaved. So it delivers the same resolution as a 2160p TAB signal BUT crucially it doesn't require your TV to handle 2160p TAB, as the TV doesn't need to do any processing to the signal other than pixel/line-matching the input signal properly - so the lines are nailed to the right polarising filters.

Alternatively there could be a TAB or SBS option - which would also (if using 2160p) not reduce the resolution vertically or horizontally - and this could be flagged via info frames I believe?