ClintonH, dear chap, with regard to your…..
'It's not that it'd still feel like a standard... -I'd- be able to either hear the strings, or feel the vibration against my body through the back of the guitar, and -I'd- KNOW it was 'wrong'....'

I tested one of the line 6 acoustics out for over an hour in Sound Control, Leeds t' other week. The 'rep' was up from Nottingham (or somewhere) and, on my asking, put the thing in 'C Modal' in under a minute for me.
I sat and played switching at will tween that tuning, standard and drop D for about an hour through a small amp designed for 'acoustic' instruments - set at a reasonably low volume - so no one might hear me struggle!
I can honestly say that right from the first notes, that I felt nowt through the body, or heard owt from the actual strings themselves.
The body is so thin and the guitars own natural volume is so low, you see.

I played a healthy chunk of my 'set' in a variety of tunings and found it a piece of cake from the outset.
Never once did I think owt was 'wrong' - it allus sounded just like the tuning I was meant to be in as I fingered the chords and tunes appropriately, just as I normally would, for each tuning.
Towards the end of the hour, the rep came back and turned the volume of the amp down to almost zero - only then did I realise what 'nonsense' was actually emanating from the strings themselves (I was fingering for C modal while, of course, it was really in standard) - I quickly turned the amp back up a bit and hey presto, once again, no 'mind-boggling effects to worry me in the slightest.

I will point out, that I didn't buy one though, lack of finance for one thing!
Secondly, I experienced a personal difficulty with the narrowness of the neck (width). I play hand-made 'Oakwood' guitars with necks made especially wide, to my own spec, something closer to classical guitar proportions.

So I'd venture to suggest no one should condemn them then, till one has had a proper go. Wouldn't want anyone to level the 'I don't like Guinness so I've never tried it' argument, eh? ;^)

It was seeing the Oysterband's guitarist use one onstage this year that made me look 'em up. But then even he didn't use it for all the acoustic guitar applications in their set. He used a variety of acoustics, chopping and changing from song to song which seemed to defeat the object of using this guitar as a sort of 'universal' acoustic.

I'll definitely keep toting the two Oakwoods to my solo gigs (proper acoustic sound), but still might consider the Line 6 acoustic yet, for use with m' electric band - to help cut down time taken for guitar changes (for different tunings), capo position changes etc, to save taking two guitars to venues - and to save my precious hand-mades getting yet more 'dings' in the rather more energetic band scenario. Also, I believe the Line 6 might just 'cut through' better against the band sound.
Heck! Talked too much again - sorry all - Cheers - HFA