Not sure where to post??

I have no experience with shetties and their energy levels, so not qualified to answer on that score. However I do think older horses would probably be better companions to match an older horse. My girl is old and stiff and I was lucky enough to get Chloe from a local charity, who is also old - not stiff, but just a bit sedater than most. She's a little bigger at 15.2 - Storm is 15hh.
 
Our oldest pony ( 36 and 13hh) is a companion to daughters two 16.3 competition TBs, he loves being 'important' and would have given in to old age years ago without a 'job', he is still however very active and gallops around with them. A lot depends on your horses mobility, if he is stiff he would find youngsters too much , size is much less important than temperament.
 
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