Lovely pic. Our of interest how do they compare to Soay? I mean in terms of size, personality etc.
Shetlands are bigger than Soays, I think Soays are our smallest natives, aren't they?
I haven't had Soays (although I'd have loved to have bought some of the ones that came over from Kilda), so I can't give you a direct comparison. But I have had a few Castlemilk Moorits and Manxes, so I can compare to those and let you extrapolate!
I find the Shetlands friendly, fairly laid back, and of course with that amazingly versatile wool in all those different colours and patterns. Not all Shetlands have very soft wool, and some can have a break in the fibre so you don't always get longer usable staples, but as a general rule, the wool is kemp-free, soft, as bouncy as it comes, and an utter delight to process.
As you've chosen two self-shedding breeds, perhaps the wool isn't of any interest to you?
It suits us better to have polled ewes, so that's another plus for the Shetland over many of the other natives.
I haven't found Shetlands to be as standoffish, flighty or wild as Manxes and CMMs can be. (Although I've also had very tame and friendly Manxes and CMMs, some lines are definitely less likely to be so. And Manxes particularly can treat stone walls - of any height - as simply vertical roadways...)
Shetland meat is strongly (and deliciously) flavoured, but slightly less at the gamey end of the taste spectrum than Manx or their mutual derivative the Castlemilk Moorit. However, it's slightly less lean too. (Not a problem for me but some people really prefer the very very lean CMM.)
I haven't eaten Soay so can't tell you how their meat compares.
You can get a decent, albeit small carcass off a Shetland after one summer, and that will be lean. Personally I prefer to give them two summers and get a bigger carcass, and a fleece as well as a sheepskin.
Hoggs will take the tup and usually do well, but I prefer to give them an extra year or even two to mature, so have them lamb the first time at 2 or 3.
The Shetland's pelvis is naturally very wide, and they are usually very milky and triplets are not common, so from that point of view she's a good crossing ewe. With the Shetland genes, the lambs tend to be reasonably small at birth, fairly frictionless in the birth canal, so crosses generally inherit the "born quickly and come out running, know where the milk bar is and are persistent in getting it" attributes which make the Shetland tup such a good choice, especially for gimmers (of any breed.)
I have found that with both Manx and Shetland ewes, crossbred lambs outgrow the little primitive parent - and I'd always prefer less birth weight and better growth postpartum, it's so much better for the mother. But, I have found that the little ewes "wear out" sooner if using a larger tup, and it's probably best to let her have at least one, preferably two crops to a tup her own size, then a couple of crops to a larger tup if that's what you're wanting to do, then back to the smaller tup again before her belly muscles can't cope with another pair of bigger lambs.
On Shetland, the usual first cross is to a Cheviot, and the crossbred ewe therefrom is an excellent commercial ewe, able to take pretty much any tup. (Cheviot lambs come out tiny and grow slowly for the first few months, really making up for it over their first winter and turning into very big sheep. So they are uniquely suited as a crossing tup on a smaller ewe.)