Hi Tim,
Taken me ages to reply but not because I haven't been thinking about it. 


>I see the spectrum or essential difference question as being like the wave/particle duality in electromagnetism
>depends what aspect you are measuring
Yes!Yes!

>Narrative is more likely to be implied or fragmented, but it's still narrative as a device. Tone - whole areas of possible tonal manipulation are possible when a poet breaks out of the typical mainstream mode. Irony becomes something else, often twisting into something extreme. Etc. 

Yes, there's a transformation. Naturally I agree with you that old excellences can still be found in new forms, - . But the transformation is radical, and it involves subtraction as well as addition. For example, the new sentence can go beyond traditional description in its extraordinary ability to suggest the multi-dimensional quality of lived experience. Still, there's a sacrifice in terms of definite assertion, though in another way the impression is needlesharp, transcending the potential of stated description. But much art and much that is possible is kind of dependent on that discursive basis.  I'm not saying it well but that's how I see it. 


>In the past I've put forward the idea that it is the modern UK mainstream poem that is the real anomaly within poetry as a whole, both with regard to the past and to poetry internationally, not the linguistically innovative. 

I kind of have an inkling of what you mean, but it's a pity you haven't been challenged on it so I'll play devil's advocate.  In all the nations whose modern poetry I have some faint acquaintance with  (US, Aus, Sweden, Spain),  the poetry that is most publicized, most studied in schools and most sold in bookshops is traditional poetry -. In Finland maybe the norm is more towards experimentalism but even in Finland there is plenty of what I see as mainstream traditional poetry. Is UK mainstream poetry so different in kind from what's marketed as poetry in other nations, or is their traditional poetry an anomaly too? UK Mainstream poetry appears to derive from an unbroken, respectable, well-anthologised tradition going back through the centuries (Anne Stevenson - Hardy - Keats - Milton - Sidney   .... that sort of lineage). ....Horace, Catullus....  Also, does the anomaly idea apply not just to poets whose work we dislike and don't read but also to poets  who I suspect you might  agree with me in admiring: Elisabeth Bletsoe? Penelope Shuttle? Kathleen Jamie even... ?   

I'm writing this not to be argumentative but because I'm eager to hear the other side of it. Maybe you've already elaborated on the idea somewhere.