No, I didn't cook them for 10 hours.
Yesterday I prepped a rack of babybacks with the 4-3-2-1 rub from BBQ USA. I didn't have enough paprika to make enough rub for the whole rack so I split it and did half with paprika and half with chili powder as a substitute. I grilled the ribs dry and didn't mop; the rubs created a crust that some might call tough but the flavor was definitely there and worth a little chewing. I have a tendency to go a little heavy with rubs and I'm sure that was a contributing factor; I also hit them hard with some heavy hickory smoke at the start. It's a good rub and I'd use it again; in fact, I'm going to use the paprika version today on my pork tenderloin. IMO the chili powder was a very acceptable substitute; aside from maybe a hint more heat I really couldn't tell a difference.