[@Kuro]
If you put the [code][h1][/code] on the outside of the sup(s), it doesn't have the overlapping issue for longer text. It does, however, have bigger line spacing than regular text. And you might want to alternate sups and subs so that it doesn't displace it weirdly on the page.

[quote][h1][sub][sup][sub][sup]Lorem ipsum dolor sit amet, consectetur adipiscing elit. Aenean dui turpis, porta vitae commodo sit amet, facilisis nec lacus. Integer malesuada leo eget diam tristique, et egestas lacus fermentum. Nullam porttitor, justo non commodo dapibus, nulla est fermentum enim, sed consectetur diam tortor vel tortor. Sed dapibus nibh justo, id tristique lectus porta a. Proin porttitor feugiat ipsum ac porttitor. Praesent nec cursus ante, tincidunt euismod elit. Sed eget finibus odio.[/sup][/sub][/sup][/sub][/h1]
[/quote]

vs.

[quote][sub][sup][sub][sup][h1]Lorem ipsum dolor sit amet, consectetur adipiscing elit. Aenean dui turpis, porta vitae commodo sit amet, facilisis nec lacus. Integer malesuada leo eget diam tristique, et egestas lacus fermentum. Nullam porttitor, justo non commodo dapibus, nulla est fermentum enim, sed consectetur diam tortor vel tortor. Sed dapibus nibh justo, id tristique lectus porta a. Proin porttitor feugiat ipsum ac porttitor. Praesent nec cursus ante, tincidunt euismod elit. Sed eget finibus odio.[/h1][/sup][/sub][/sup][/sub][/quote]

Also, it looks better with an H3 as opposed to an H1 - almost usable, even :)

[quote][h3][sub][sup]Lorem ipsum dolor sit amet, consectetur adipiscing elit. Aenean dui turpis, porta vitae commodo sit amet, facilisis nec lacus. Integer malesuada leo eget diam tristique, et egestas lacus fermentum. Nullam porttitor, justo non commodo dapibus, nulla est fermentum enim, sed consectetur diam tortor vel tortor. Sed dapibus nibh justo, id tristique lectus porta a. Proin porttitor feugiat ipsum ac porttitor. Praesent nec cursus ante, tincidunt euismod elit. Sed eget finibus odio.[/sup][/sub][/h3]
[/quote]