I'm not sure that setting the seed to the next number in logical order is the right way, Personally I would be setting the seed to start from a number somewhat larger than the current, simply to avoid the chance of collisions.

In your example rather than setting the seed to Current+1 I would be inclined to set it to 100 (or some other factor of 10 depending on the current position), this way I could easily Identify the rows that were assigned by the new method and track any issues that were being created.

As you state in the article,the introduction of Denali solves this type of problem with the new SEQUENCE statement.