Bob, I assume you are asking whether the top DIII programs are "pretty competitive?"
Actually, these players compete just as "hard" as DI teams compete. There is no difference between DI and DIII in terms of the effort and committment required. In the Fall, you will be lifting at 6am, be running the mile under 6 minutes and be on the field 3-4 hours several days per week. Are they DI? The answer is no. Will you find pitchers who throw 90? Occasionally you will. Will you find DI players at this level? Occasionally. Top DIII's such as Southwestern, McMurry, Hardin Simmons/Trinity play the game with as much intensity/competition as you will find anywhere but it is not Texas vs Rice in terms of overall skills from top to bottom. If you are not fully committed and very talented, chances are you will not have much success at the top DIII programs in TX and your teammates and coaches will let you know that right away.
A major difference from DI is the fact you are not entitled to anything different that every other student. So, you are expected in class, no tutoring or special academic treatment and many times you may end up running from class to practice, which has already started.