In my templates I use things like:
Code:
{if:!product.countImages()gt1}
Some code
{end:}
Flexy, doesn't allow for the same "flexibility" (pun intended) as Smarty. There is good reason for this, it forces you to put the logic where it belongs, in PHP rather than the templates. There is no cool "array_reverse" that I know of.
You will have to determine the class that displays the thumbnail. Extend the class, assigning your own value for thumbnail. Then {getMyThumbSrc()}.
It's a pain for someone with a design oriented background. But hardcore devs will appreciate that this a better way. XC5 has truly separated design from logic, but in doing so made the two camps depend on each other more than ever before. I think as a whole this is a very good thing. For your individual one-man (or woman) project it can be a real hassle.