We chose this solution because it was the easiest one. Otherwise we needed to change the DBM API.
The percentage is not an exact one. It's the percentage related to a probability density function. When you increase it, you increase your chance to get your database to be "optimized". The only exceptions to these rules are the 0% and 100% percentages which disable/enable optimization completely and regardless of the PRNG.

It was tested on 3.2.x by Bishwa and I and it works as intended.