NEW YORK (CNN/Money) - UnitedHealth is at it again, this time gobbling up Oxford Health Plans just two months after it completed a merger with Mid Atlantic Medical Services.

The deal would expand UnitedHealth's presence in the key Northeast region while giving Oxford members more choices outside of the area.

In the insurance game, bigger often means better coverage but will it also mean less service?

Potential upside: The consumers most likely to be affected -- positively or negatively -- by the merger are those insured by Oxford Health, the smaller of the two companies, according to industry observers.

UnitedHealth has invested a lot of money in its information technology and clinical quality management systems, so the benefits of that research may be shared with consumers in Oxford's plans. Clinical quality management systems track patient care and are designed to ensure that physicians are meeting the insurers' minimum standards for quality care.

A larger network also equals more choices as plan members may have more physicians to chose from. Oxford is primarily concentrated in the New York, New Jersey and Connecticut areas, so their members may benefit from the national reach UnitedHealth offers, Paul Ginsburg, president of Center for Studying Health System Change, noted.

And the newly merged insurer will have more muscle to flex thanks to its larger customer-base, making it a more aggressive negotiator with patient care providers.

"United already has a significant network in the New York metropolitan area, and this would add to that," said Tom Billet, a senior consultant with Watson Wyatt Worldwide.

Potential downside: A more aggressive negotiation stance could alienate some doctors, though, said Arthur Levin, the director for the Center for Medical Consumers.

He says that doctors are increasingly opting out of insurance plans they don't like, instead asking people to pay upfront or accepting a limited number of plans. It may also force physicians to concentrate more on patient volume, rather than on individual care.

YOUR E-MAIL ALERTS Mergers and acquisitions United Health Oxford Health Plans Incorporated or Create your own Manage alerts | What is this?

"Anytime health plans are more aggressive about negotiating rates, consumers tend to suffer," said Mark Scherzer, legislative counsel for New Yorkers for Accessible Health Coverage. "Affordability is important, but if doctors only have 6-8 minutes to spend with each patient because they are so financially pressed by the plans, it's not in the patient's best interest."

Regional competition within the New York tristate area may also suffer.

"All of these plans compete with one another for the business of employers," Levin stated. "These plans are competitively marketing themselves. It's very price-driven. They claim there are other factors, but it is predominately price-driven."  

CNN/Money senior staff writer Jeanne Sahadi contributed to this report.