According to the '07-'08 Vacation Planner, exchanges through II are as follows:
1 BR - low season - 124 pts
1 BR - mid season - 144 pts
1 BR - high season - 160 pts
2 BR - high season - 207 pts
2 BR - mid season - 252 pts
2 BR - high season - 270 pts
No mention of studios being available. However, a 1 BR through II may not be the same as a 1BR at
DVC. We traded out in the spring for a 1BR and got what I considered to be a large studio. It was just one huge room with a microwave kitchen (no stove or traditional oven). The sofa was next to the bed and there was a fairly large kitchen table. There also was no washer/dryer in the unit. While it was fine for DH and myself, it definitely was not a WDW 1BR.
Point-wise it was 23 points more than a studio, but 76 points less than a 1BR during Adventure season at Boardwalk.
All three calls I made to trade out were made at night. Only once was not able to get something in a location I wanted (I pretty much knew that before I called - popular location in high season/short time frame). While trading out may not be the wisest use of your DVC points financially, DH & I will occasionally trade out if we decide we really want to go somewhere and have as little OOP expenses as possible.