I know a guy who once put in above pineveiw falls at 4'6'' on the rock in a dagger approach
his wife argued him out of the river for a scout.
The dagger approach is one other boat to look at but you would rather have an xp10. The 3 cross over boats I know of are from jackson, LL, and dagger.
Given your description of needs it sounds like flat water and moving water are your closest options.
The boat you have chosen is best suited for both flatwater and ww rivers. People here say to get a creeker, or playboat. this is good once you have a roll and like the sport. a playboat is AWESOME to have in a flat water enviornment because after you learn to roll you can do flat water tricks. It is NOT a boat you want for lake paddles and flat rivers. A creeker will spin in circles on a lake, not an option.
If you do not have to spend a ton to like this sport, but do not sacrafice what you need, in this case a skeg or keel, what ever you want to call it. it is important to enjoying flat water, having it retract will help in whitewater and learning to roll.
A side note, those lake boats at bass pro with the bow and stern skegs molded into the shape are flat bottomed and REALLY hard to roll so save your money there.
if you do chose the XP you will get the most out of the down river experiance. It is the most durable well outfited boat in its class, jackson is great too but in this case...XP.
You will be a river runner. it is great to feel the water underneath you. in and out of eddys, ferrys, boofs, side surfs, it is no playboat but you can do ALOT with a river runner.