How would leg of lamb work as a substitute for lamb shoulder? Looking at the citrus/olive/lamb recipe got me wondering.

I defer to Pierino - the shoulder is just the meat from the area above the fore leg rather than the rear. The farm I usually purchase from packages lamb leg meat which definitely requires a liquid braise or stewing to become tender whereas their shoulder meat can be grilled and still be tender. Due to the shorter cook time in this recipe, I stuck with shoulder meat. However, this farm's leg meat is likely different than "leg of lamb", which is not something I generally cook. Maybe they cut from further down the leg or shank.

Should be fine. The leg and the shoulder both get lots of exercise while they are still attached to the lamb. Seriously.

Leg works fine flavor-wise, it just takes longer to cook to tender.