funnyperson I really don't think I could claim to be a grass expert, I am more of a bumbling and occasionally fortunate enthusiast whose random efforts work out OK sometimes.
but, if it helps...
Your bank sounds lovely, and I am amongst the many hoping to see a picture of the buddleia peacock. I am envisaging cloudy golden grass cushions for the peacock to luxuriate and spread his tail.
I imagine it is fairly dry on the bank (although most grass are pretty tolerant of most conditions).
Anemanthele lessonia could work for you there, it has a particularly beautiful curved, arched shape which trembles and quivers and rustles. The young leaves have a reddish tinge to a light green, and very quickly they develop a golden glow. The flowers appear from about June, and they are slender reddish-golden plumes which curve over in line with the whole clump, they don't stand proud. it is reasonably tall, but not over your 1m limit.
On the Knoll page you have probably seen Carex Testacea, I have not seen this for a while, but it may be more the fully golden colour that you may be thinking of.
otherwise some miscanthus would be very happy on a bank, they rustle and move happily, although many varieties are too tall for your limit. Perhaps Miscanthus Purpurascens?
I wish you luck with the sanguisorba, mine disappeared within a few months, never to return, and I did think it might be too dry for them, this article suggests they like a bit of early wet and humidity.