We've had three, and absolutely love having them. They are famously quiet around the house, and mainly doze - much like greyhounds.
The first two (female if it matters) were easy to train (by me), wonderful on the lead, and great with people and other animals (cats as well as dogs). Our current one is just over one year old and has been 'trained' by DH. He is generally wonderful, but prone to getting over excited at the sight of a cat in the street. He shows no interest in deer what so ever (fortunate where we live). I feel he needs more lead work, but since it is almost exclusively DH who walks him, that may take a while. They have all been slightly free spirited
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Our first lived to 11 but the second was only 5 when she had a catastrophic heart problem. Insurance for the current one is £1800 per year.
Contrary to what pp suggested, none of ours have been big eaters. They eat less than a labrador eg. Due to the importance of ensuring good bone and joint health though, it needs to be high quality feed. Our puppy is already over 47kg. He won't get much taller but will fill out a little I hope.
I am surprised by the comment that they moult a lot. That has not been our experience at all. They certainly leave less hair around than any other dog we have known (mainly labs, collies and spaniels, so perhaps not typical).
After the puppy stage, one big walk and a couple of shorter ones would be fine. They can go longer if you fancy a big walk, but usually don't need it. We usually have one walk of about 1.5hrs and another couple of sniffs around the block.
Personally, for your DM if it is a 'look' thing, I agree with pp who suggested a bedlington/whippet cross. I believe there is a FB page for them where there are often litters or rehoming. Alternatively, if she is stuck on a deerhound, perhaps contact breeders to see if any of them have a returned one, adult or younger.
The Deerhound Club has a website and FB page, but they are run by older, not very tech savvy people so are not whizzy or sparkly at all. Do search for them though.
Good luck whatever she decides.