My primary reason for not rebuilding with the same rims is that I don't want to waste time and money on a ****ty product. Number of spokes is just a bonus. I don't doubt that you could ride a 24 spoke rear wheel for some amount of time without problems, I just see no reason not to go with a more stable setup if I am starting from scratch anyway.

Come to think of it, why did you switch rims if you were in the exact same situation I am?