Illustrator is one of the worse applications to open a pdf with. It doesn't release the multitude of clipping masks inherent in a pdf, it flattens multilayer pdfs to a single layer, and the list goes on.
I've never bought fonts because of either online testing or trial licenses. Neither has a cut-down version nor a free style been an inducement. I purchase fonts either because the job dictates it or because I like the shape and glyph coverage I desire or need is present.
How a site looks is also not a consideration to me as long as I can see what I am buying. How well a site works would be an issue to me if the font is available elsewhere.