Ultimately, the signature will hard-limit at 200 pixels. So, I have no problem increasing the number of images, but keep this in mind - anything after 200 pixels will be sliced off. It's to cut back on signature spam, and you can fit a lot in 200px height.
This isn't resolved, but will be once I have time to remember my name again.
Done. The limit was increased to 15 images. Please be aware, however, that the forum will slice your signature off at 200 pixels in height. So, if you're going to do multiple images, you may want to tile them horizontally.