Sorbus garden?

We aren't experienced gardeners and would be grateful for any advice about our sorbus aucuparia plan.

We live in the Derbyshire Dales area of the Peak District. Our front garden has never, ever been gardened. It's a south facing extremely steep hill, about 40ft wide by 50 ft long. We aren't experienced gardeners. We're thinking of making it a garden dedicated to sorbus aucaparia, with some variations (if that's the correct term) like sorbus scalaris, sorbus huphensis, sorbus huphensis, etc. We've already put 6 ft hazel wattle hurdles along the boundaries of the garden, and we would like to simply grow the sorbus scattered along the edges of the garden, like a wildish loose hedge, just trimming parts of it if it starts to block the lovely views. We would have just one sorbus aucuparia growing as a solitary tree part way down the hill. So the garden would just consist of a border like a mixed wild high hedge except that it would all be sorbus, and one sorbus tree, and wild grasses & flowers.

We want to do this for aesthetic reasons but, aesthetics apart, are there likely to be any disadvantages to having an all sorbus garden? Are they more likely to get diseases if there are lots of them? I would prefer not to have a mixed wild hedge, because I think a sorbus garden would make a change & be beautiful in its simplicity, but does a mixed wild hedge offer better protection from diseases?

I realise that if our sorbus were all struck by fireblight or some other big problem, it would mean we might lose all our plants at once. What I wonder is, would our sorbus be more likely to suffer if there were so many of them? I was thinking the "hedge" around the garden would consist of about 23 sorbus, plus the sorbus tree in the middle.

Thank you for reading.