So a long-gestating merger of the two companies -- expected to be approved by the Federal Communications Commission in the next few weeks -- would initially mean duplication of content. But radio industry insiders anticipate that much of that redundancy will be eliminated once the deal is finalized.

Some have speculated that reducing redundant formats could enable record labels to better target their promotion resources toward one station. But in general, most of the label promotion representatives polled by Billboard -- especially those specializing in niche formats -- think fewer stations means fewer promotion opportunities.

“It's great that their combined (channels) will have a larger audience but it's also at the expense of the exposure," Virgin Records VP of promotion Dave Reynolds says. “It takes away 50% of my chance of being exposed correctly."

Brad Paul, senior VP of promotion at Rounder Records -- a label whose bluegrass releases benefit from the 24/7 national exposure they get from Sirius and XM -- doesn't like the idea of one less national outlet. “If the argument were being made that it's a good thing because I could economize my effort, heck, I'm not about economizing my efforts, I'm about having opportunities to get these artists' music exposed to as many listeners as possible.

“Both networks offer different ways to feature and launch a new project," Paul says. “I feel good about having both those options to go to."

Sirius and XM, with a potential combined audience of more than 17 million subscribers, have downplayed consolidation of channels, instead focusing on a la carte plans and packages that will allow subscribers to maintain their subscriptions with one service while choosing from the best of the other. But in any such consolidation, duplication of services is often the first thing to go when companies are looking to cut costs.

Stern aside, the most popular streams on both XM and Sirius are music channels, according to Arbitron. The top channel on Sirius after Stern, who draws 1.2 million listeners, is Sirius Hits 1 with 653,000 listeners, while the top station on XM is Top 20 on 20 with 1 million. Both streams focus on today's hits.

“It's very rare to find a station like Sirius Hits 1 or XM 20 on 20 that will put in a new song and play it 21, 28, 35 times a week right off the bat," Virgin's Reynolds says. “That's really exposing a record."

While few executives that Billboard talked to could cite a specific case of Sirius or XM breaking an act, several cited satellite as a significant promotional platform. “Satellite radio definitely had a lot to do with Sean Kingston's career," Koch Entertainment VP of urban promotion Shadow Stokes says.

Rap stations XM Raw and Sirius' Shady 45 have helped break a number of hip-hop acts, he adds, citing Sheek Louch, AZ and Yung Berg.