I like Lamb and can't get enough at a reasonable price.
The two ways I've cooked Lamb are low and slow 225 -250 and hot and fast 400 - 425, all the other preparation is the same.
Slit all over every 1" or 1 1/2", put a slice of garlic into every 3rd slit, a sprig of thyme or a Rosemary leaf into each of the other slits. Rub all over with oil, then rub them with sea or Kosher salt.
Stick them on the pit, and wait for them to cook, if you are cooking low and slow I go to 145 in the thigh for a large amount of pink in the meat, if you want it more cooked take it to 155 or 160 internal, I don't personally like to go much further than that. If you are cooking hot and fast, you'll have reached the same point when the flesh of the thighs starts to crack, when you cut into it the middle meat will still be pink, if you like it more cooked take it on a little further as with the low and slow.
I don't have a smoker big enough for whole Lamb but the family used to have a yearly BBQ with a rotisseried whole Lamb cooked over charcoal outside, with a corrugated sheet metal to direct the heat up at the Lamb.