Question about using h1 tags for banners

I'm making a small site for my business, will have perhaps 15-20 pages. I'm playing with creating a CSS banner within an h1 element - a graphic for a background, and then lots of top padding so that I can have an optimized slogan written in real text along the bottom edge. I have overflow set to "hidden" so the text won't overflow the banner if someone cranks up their text size a few notches.

I know that h1 tags weigh relatively heavily in page ranking, and that you should only have one per page. But what about site-wide? Should I change the h1 text on every page, or is it OK to have the same text in the h1 tag on every page?

Also, does the size of the text matter? Currently I have a small text size in small-caps. I'm not actively trying to hide the text, it just looks better along the bottom edge of the banner this way.

I personally can't understand the value of having these same words as your H1 on every page of the site. I would just slap it in an image and use the valuable H1 for the optimized title of the page.

It sounds like you are allowing some design impulse run your SEO efforts.

How much traffic is the H1 in that banner going to fetch? More than your page titles?

Size doesn't matter (that's what she said)