I live just south of the Truman Lake area. Hunted there a lot a few years back, but have good ground to hunt much closer to home, so haven't made the drive for close to 10 years. That said, if I couldn't hunt until the 3rd week of the season, I wouldn't hesitate to go there. There actually are a lot of pluses involved in the decision to hunt MO that week.
First of all, a LOT of hunters will be tagged out. That, plus the fact that most non-resident hunters will, due to our goofy "one bird the first week" regulation, show up the first weekend of the season, and will be back home before then, translates to a lot less hunters in the woods. Sure, a lot of birds will have already been killed, but even on many of our public areas, there is a substantial carryover of mature gobblers. A few years ago, I had a tough time filling my second tag, something I haven't failed to do for over 20 years. My normal private land spots hadn't been productive, so, kind of on a whim, I drove to a small conservation area about 10:00. No one else was there (this was on Saturday). As soon as I opened the door I heard gobbling. Long story short, I, after about an hour, bagged a nice tom barely out of sight of my vehicle. As near as I could tell, there were 5 adult gobblers on the area that morning.
Truman Lake, isn't, obviously, your only option, but if you have hunted there before and know where you have found birds in the past, that in and of itself is a check mark in the plus column. Wherever you decide to go, good luck.