A small amount of JavaScript is added to each product displayed. This can safely be ignored on non JavaScript browsers. It won't affect navigation or basic functionality.
Radio buttons for selecting product choices are now dynamically created by JavaScript. This fails safe (via <noscript> tags) on non JavaScript browsers. You'd just lose the additional images.
what I don't want to do is upset other functionality around other pages, I am just clarrifying that if I alter the original templates, I won't affect anything else around the system.
I'm quite happy taking traditional backups and documenting what I have done