Slow grilled sirloin rib roast

With our new-to-us grill that my husband just got all hooked up (he had to put in a gas line for it), he told me he wanted to make a roast on it an cook it slow for a few hours. So, off I went to Howard's Meats, a meat market in nearby Munster, Indiana. I asked the butcher for a suggestion on a good roast to make on the grill. He pointed out a couple and I ended up with a sirloin tip roast.

I took it home and mixed up a little olive oil, Worstershire sauce, some garlic, Trader Joe's Everyday seasoning, freshly ground black pepper, dried onion, smoked paprika and sea salt and rubbed it on then poured the remainder in a ziplock bag, put the whole roast in there and let it marinate over night.

Hubby put the roast in foil and put on the grill the next afternoon - indirect heat at 250 for five hours and this is what we got:

Hubby said it was a little dry for him. Call me crazy, but I like my roast a tad on the dry side rather than swimming in fatty juice. It tasted good to me. I had some baked potatoes that I finished off on the grill with some olive oil and seasoning and added green beans to the plate. The meal was a winner in my eyes. :) Next visit to Howard's I'll get a pork roast and give it a try. Any tips for me on grilling roasts and on keeping it a little more moist to please the hubs?