Is This Upgrade To The Powershot A720 Worth It?

Hi again:

I'm using a Canon A720 to try and photograph coins (see previous thread). Compared to what is available today, it is a bit outdated, it carries 4 megapixels and a 4x optical zoom. I spent some time taking shots with rulers in it, and determined that in macro mode, the camera is really only capable of about 2.8x zoom before the lens runs out of focal length. The field covered is 87mm x 65mm, which means the dime I've been shooting only covers about 25% of the field.

Canon sells a lens adaptor and a "close up" lens, which allows the camera to take macro shots with a field of 39mm x 29mm. which improves the magnification by 2.2x, resulting in a "real" optical zoom in macro mode of a little over 6x. The dime would then fill a little less than half the field, effectively doubling the resolution of the camera. The upgrade costs about $100.

So, the question is, do I upgrade this camera, which I like a lot, or is it time to get a new camera with better optical zoom and more megapixels? Anyone have experience with upgraded lenses on the Powershot cameras?

Thanks in advance,

Jim