The old "rule of thumb" 2.5 x RAM is obsolete and has been since 2.4 kernels.

Linux' use of swap is frighteningly sophisticated.

As I see it, popping things which will be seldom used into swap makes sense. Although swap is (much) slower than RAM, the more RAM you have available (due to use of swap) to serve the more frequently called things the quicker the job will be done.

In short, the only argument is swap or no swap. Use more than 1/2 Gig or so and you're just wasting space which could be filled with .oggs or Buffy movies............