I haven't smoked and reverse-seared lamb chops before, but we have grilled lamb chops many times. IMHO, an IT of 150 deg for lamb is overcooked and will lead to tough and dry lamb. I know that IT is mostly a matter of personal preference, but unless you have an aversion to pink meat, I think you'd be better off smoking to an IT of 110-120 deg, then searing to get you to medium-rare. Searing time will depend on how thick your lamb chops are. Lamb is usually pretty fatty, so keep an eye out for flare-ups while you sear.
Good luck, and let us know how they come out.