The Rising Stars, which include a 927×250 Billboard and a Sidekick that expands to 850×700, are generally bigger, bolder and more interactive than their older cousins like the Skyscraper, but marketers appear to be blind to them.

According to ad network Undertone Networks, less than a third of the 100 marketers it polled have even heard of the Rising Stars ad units. The 500-plus agency employees were more familiar with the units, with nearly 70% of those surveyed indicating they’ve heard of them, but Undertone says that overall adoption is slow.

The addition of the Rising Stars units last year was the most “radical” update to the IAB’s lineup in years, but without substantial inventory, media buyers have only so much opportunity to put them to use, even if they’re interested, which many of those familiar with the units seem to be.

Bigger, bolder, but bad for experience?

Obviously, the fact that Rising Stars ad units aren’t rising fast shouldn’t come as a surprise. As much as advertisers want bigger and bolder, widespread overnight adoptions of any new ad formats are unlikely.

But it remains to be seen whether Rising Stars units will ever take off. For publishers, units that play a more prominent role in the user experience, and have the potential to interrupt it, are a double-edged sword. Yes, Rising Stars inventory might be more appealing, and thus capable of being sold at a premium, but if the ads annoy users and drive them away, they might be a net negative.

Also complicating matters for the new Rising Stars ad units, perhaps, is the rise of native advertising, which offers advertisers the ability to be a more prominent part of the user experience, but in a very different way. Although native advertising isn’t a panacea, and many advertisers seem confused about how to approach and use native ads, it is possible that the trick to making online ads bigger and bolder is to make sure they don’t look like ads, something that the IAB’s new ad units don’t accomplish.