Argue all you want about Flo Rida's skills as an MC compared to such lyrical masters as Nas, Jay-Z and Eminem. But there is one thing you cannot take away from the Carol City, Florida, rapper born Tramar Dillard.

He moves units.

Lots and lots of them. Including his latest ear candy hit, "Whistle," which currently sits atop the iTunes and Billboard Hot 100 singles charts, with global digital sales north of 4 million.

Since his first #1, 2007's debut smash "Low," through the #1 "Right Round" (which broke the "Low" record for most digital sales in one week with 636,000) and the Wild Ones hit "Good Feeling" (#3) and his latest chart-topper, Flo has achieved the kind of chart domination that most rappers can only dream of.

In addition to his top 10 hits on the Hot 100, which also include "Sugar" and "Wild Ones" (#5) and "Club Can't Handle Me" and "In The Ayer" (#9), Rida has appeared on huge songs by other artists, including David Guetta's "Where Them Girls At" and Jennifer Lopez's "Goin' In."

But is he the best-selling rapper of the download era?

"It depends on what you call hip-hop," said Keith Caulfield, associate director of charts at Billboard magazine. "A lot of people consider artists like Flo Rida to be crossing genres. He's a rapper, but at the same time he's been more embraced by pop audiences and had way more radio airplay on top 40 stations."

Caulfield said the dance-ability of Flo Rida's songs puts him in a very different category than someone like Eminem, who is also a rap sales champ. But whereas Eminem excels at moving album units as well as singles, Flo Rida's albums have had mostly modest sales compared to his millions of song downloads. Flo Rida's best-selling album is his 2008 debut, Mail On Sunday which has sold more than 443,000 copies to date.

But, according to Caulfield, on the list of all-time best-selling digital songs from 2003 to the present, Flo has five entries in the top 200. Leading the pack is "Low" (#7, 6.4 million), followed by "Right Round" (#28, 5.2 million), "Good Feeling" (#99, 3.4 million), "Wild Ones" (#123, 3 million) and "Club Can't Handle Me" (#165, 2.9 million).

Dillard has no illusions about his place in the MC pantheon. "If you [ask] if Flo Rida is hip-hop, which I am and I consider it," he told MTV News earlier this year. Citing such fellow envelope-pushers as Outkast, he said he's always looking to find creative outlets for his music that are rooted in hip-hop. "When I'm in the studio I'm thinking of every different type of melody ... flow I used to hit back in the days and use those ... but for the most part I've created my own lane."

As for his embrace of EDM and dance music, Flo said he grew up listening to all kinds of music, including the church songs his seven sisters sang in a local gospel group. "I like to take music from everywhere and put it in my style and let it be accepted," said Rida, who was originally signed to Poe Boy Records, former home of fellow Carol City rhymer Rick Ross. "That's what gets me going. I'm influenced by all types of music. At the end of the day I want to be the guy who experienced music in all type of ways, with hip-hop being the roots of it."

Though he was threatened by Taylor Swift's "We Are Never Ever Getting Back Together" this week, Flo still holds the all-time record for most single-week digital sales with "Right Round" (636,000), while "Low" (467,000) sits at #10 on the list. No other rappers can lay claim to even one spot on that tally, though other acts that incorporate rapping and dance beats, including the Black Eyed Peas and LMFAO, are also in the mix. In fact, the will.i.am-fronted band can lay claim to the biggest-selling download of all time with "I Gotta Feeling" (more than 8 million copies).

What Flo Rida underscores is how the hip-hop tent is much bigger than people are willing to admit, according to New York Times pop music critic Jon Caramanica. "He comes from inside the [hip-hop] tradition, but early in his career he was fortunate enough to have crossover records and he became more relevant in that space," he said. "That fact that he's had that success means there's a huge market to be tapped and if a rapper-rapper isn't going to do it, [Flo Rida] is more than happy to pick up that slack, and those royalties."

We're well past the time when hip-hop can be reliably defined as one thing or another, and the boundaries of the genre are rigidly well-defined. That said, Caramanica noted that Flo Rida isn't really played on rap radio, and he's not the cognoscenti's choice, but he is doing what rap has always done: throwing away the rule book and changing.

"Some people are quick to dismiss him because he doesn't sell albums and he's not taken seriously by hip-hop fans," said Caulfield. "But at the same time he's laughing all the way to the bank because he's selling jillions of tracks and making money off every one of those 99 cent or $1.99 songs. On the one hand you can be a well-respected hip-hop artist and sell 200,000 copies of an album or be Flo Rida and sell 6 million copies of a track and have a robust career and be quite comfortable."

So, is Flo Rida the best-selling hip-hop singles artist of the past five years? Caulfield said it's all in how you define "hip-hop," but what's indisputable is that Rida has ridden his pop-infused rhymes to a formidable mountain of sales.

His top five digital hits have racked up sales of 20.9 million, putting him just ahead of Slim Shady's tally for the same number of hits (19.5) and Kanye West (17.1), and well ahead of Jay-Z and Lil Wayne, according to figures from Nielsen SoundScan.

"One thing you can say is you never have the sense that Flo Rida is in the business of turning sh-- down," said Caramanica. "You present him with a dubstep track? 'I can do that!' A more dance track? 'I can do that!' The reason he's been able to be 'experimental' in a pop context is because compared to Rick Ross he's not the most technically gifted MC and not most creative lyricist. But the thing he's done is he's said yes to a lot of things and fortunately for him some of them have hit."