Hi Julia,
 
Like Richard, I'm up against the clock - and also the effects of my impairment...  But a few thoughts:
 
In case you're not aware of it, you might find my article useful - it's in both Jenny Morris' Encounters with Strangers and Colin Barnes' Exploring the Divide:  'Renewing the Social Model'.  I had been very involved in the disabled people's movement for many years when I wrote this, firmly wedded to the social model.  However, as my impairment increased (I too have ME), I felt more and more alienated from what was happening in 'the movement' and less and less able to contribute.  I guess I wrote this piece as a way of trying to work out what was going on.
 
I'm utterly convinced of the value of the SM.  I think it's fully able to include people with illnesses, as well as the range of other impairments, and I also think as a model and a tool for change it's perfectly capable of incorporating the implications of impairment without losing any of its power for explanation or change.  However, I'm much more cautious about our (current) capacity as a movement to apply it wisely.
 
I think the problem lies in our not grasping the range or complexity of issues to do with both disability *and* impairment.  In the end, during periods of better health, I am brought overwhelmingly face-to-face with disability.  At my illest, when I have no choice but to retreat from the world (removing discrimination would delay this retreat, but at my very illest, the retreat becomes inevitable), the idea of external structures, discrimination, etc seem almost laughable - not that that means they cease to exist, but that my existence is almost so completely apart from any kind of social world, that it scarcely touches me.  That's one of the reasons I believe impairment and disability can't be fully understood, one without reference to the other.  The two relate and for many/most of us - whether because of fluctuating impairment or changing disability - are constantly shifting.  Disability is not about or caused by our bodies, but it *impacts* on our bodies, and our bodies on it.
 
When I was at my illest, there was a 'threat' (both spoken and implied) from many disabled people that I should not mention the fact that my body was (and is) so very hard to live with/through.  I have been told that ill people do not have a place in 'the movement' (that our 'issues' are different), that by saying my body causes me grief I am in denial (of what exactly is never specified) - oh, etc, etc!  But the social model never said any of this stuff - it was all down to the way that individuals were applying it.  Removing discrimination from my life won't make my body well (though it will make my life dramatically better) and (after all these years of discrimination), removing my illness won't mean that discrimination ceases to impact on me.  Both impairment and discrimination have a massive impact on my life - in different proportions at different times - and, regardless of how models are applied, the only feasible way for me to carry out my life is to acknowledge both.
 
Where I think we need to be very cautious in suddenly seeming to 'reclaim' impairment, is in the world 'out there' where there is a genuine risk that many people will say "A-ha, we always said disabled people were tragic".  For our campaigning work, for non-disabled people wanting to do something, perhaps this debate is purely 'academic' - and for these purposes, I firmly believe that disability needs to be the public focus.  But behind the scenes, it becomes much more important.  For our own understanding and, more importantly, for our ability to fight against disability, strongly and effectively, I think we have to acknowledge the complexities that are really going on behind the scenes.