One of my good friends from my hometown plays DII college tennis and he is only a 3.5. I hate the generalizations about divisions. I play DIII and am a 4.5 and certainly not even close to the top of DIII tennis.
As far as the open tournaments go I think it's great you played. We always have a few 3.5's in our open draws and though they may take some beatings it helps them improve faster. In fact I started out my open tournaments with a 3.5 rating.
"If you aint first, you're last!"