Updated from 7:31 a.m.Nextel ( NXTL) continues to hit on all cylinders. The cell-phone service provider doubled second-quarter operating profits Wednesday, while posting stronger-than-expected subscriber growth and reduced customer defections. But the company's shares slipped 2% as investors continue to weigh the pros and cons of the fast-growing, debt-heavy carrier. For its second quarter ended June 30, the Reston, Va., company posted earnings of $1.3 billion, or $1.17 a share, after a tax-valuation gain. That's up from the year-ago $281 million, or 27 cents a share. Revenue surged 29% from a year earlier to $3.3 billion. Excluding charges and gains in both periods, latest-quarter earnings jumped to $608 million, or 55 cents a share, from the year-ago $288 million, or 28 cents a share. Wall Street analysts had expected Nextel to post earnings of 50 cents per share on $3.2 billion in sales. "Our second-quarter results reflect continued progress on multiple fronts and we are on track to meet or exceed our 2004 guidance," said CEO Tim Donahue. "Subscriber quality improved during the second quarter as reflected by an increase in average monthly revenue per subscriber (ARPU) and a reduction in customer churn. For the year ending in December, analysts surveyed by Thomson First Call expect the company to earn $2.09 a share on revenue of $13 billion. On Wednesday, Nextel said it added 546,000 subscribers and posted a monthly churn rate of 1.6%. The company said average revenue per user rose to $70 from $69. Some industry observers had expected Nextel to post a monthly customer defection, or churn, rate of 1.4% for the quarter ended in June. That would be one of the company's lowest rates ever and a far cry from the 3.7% rate of departures at troubled AT&T Wireless ( AWE) last quarter. Nextel was also expected to add about 500,000 new subscribers last quarter.