I do these often and with great success.
First I score both sides. Then I marinade in balsamic vinegar, olive oil, crushed garlic maybe a little soy sauce and worcestershire or even dry sherry. the acid breaks the meat down and the oil extracts the spices and locks into the meat.
after 24 hour marinade I brush with a little honey and some black pepper and salt. I throw it on a hot grill and cook like a fat steak. Sear on both sides then roast to a medium rare. it is important to slice against the grain.
The meat is tougher, so I think an acidic marinade is crucial
I haven't reverse seared one, but don't see why not. (that whole idea is new to me and I haven't had the chance yet)
But these sirloin tips are one of my favorites to cook with the above procedure when I find them on sale or manager's special.