If slaughtering for meat, they are not ready until about 16 months, so you need to overwinter. Feeding through winter would mean less "profits". Our butcher said that our Soay butchered were about half the weight of his this year lambs. Meat is in our opinion quite different from usual lamb in that there is far less fat. OH loves it but is not keen on normal lamb as he finds it too fatty. Went to look at the carcass compared to the butchers Lleyn carcasses. Outside of the Soay were dark with little fat. Lleyn had thickish white fat layer all over. Don't think you could take to market ..... be laughed at I guess ..... so would need to sell privately. We have filled our freezer and sold to family. Not commercial sheep. Not sure if you could ever make a profit by selling to restaurants etc.
As a breed we have found them easy enough to keep. Still need care as you would give to any breed but ours seem to have done well. Kept for nearly 4 years and no strike .... we do use Crovect routinely and check as you would any other sheep. We worm at lambing and fluke during the year but so far no scouring or problems with worms.
Ours have all self shed or we roo ..... if we want the wool. If for some reason they don't shed then you would have to shear as norm.
No foot problems yet

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They haven't proved to be escape artists which we worried about. We have normal stock fence with a top bar. Most boundaries also have mature hedges, though. They haven't jumped hurdles when penned but would do so with ease.
All are bucket trained and come running across 3 paddocks if they hear you. We just keep handling quiet and calm but guess that works best with all sheep anyway.
All lambed outside without help and no problems with mothering.
Light sheep so easy in a way to handle/turn but local shepherd found them tricky in the sense that they twist and wriggle more than his commercials or Jacobs. My 12 year old daughter can handle them .... inject, drench etc.
Only kept Soay so can't compare with much else. Helped load some commercials for local farmer the other day and the haulier said he'd just had a merry job loading commercials at another farm ..... jumping stock fence with barbed wire tops and clearing hurdles. Think a lot of it maybe knowing your sheep, thinking of best ways to pen and handling to suit.
I like Soay.