Like Duffy, they have watched Narberth's change from a blue-collar community - it was created by the Pennsylvania Railroad for its workers in 1895 - to one of two-paycheck professionals looking for quick commutes and access to Lower Merion's public schools.
First-time home buyer Jonathon Staszewski, who moved to Narberth from Center City in April 2011 with wife Mariel and daughter Viera, now 11/2, often works late and stops by the market on his way home from the station.
"They make great hoagies and carry a lot of Italian food, which I love to cook," says Staszewski, who was attracted to Narberth by its location (he and his wife work in the city) and prices below what they had seen for houses in Philadelphia.
"It has a first-run movie theater, activities for kids, schools, and even a Dickens Festival in December," he says. "Everyone here really does know your name."
Narberth's demographic shift has had a huge impact on its real estate market, where pre-World War II two- and three-bedroom houses predominate.
"First-timers used to come here and buy starter homes with the aim of trading up to a bigger place elsewhere on the Main Line," says Duffy, who grew up here and opened his office on Haverford Avenue in 1978. "Now, however, they come here and they want to move within the borough when they need a bigger house."
The low entry-level price point is about $165,000 - for a rowhouse that needs work, or a condo. High-end, he says, is $700,500 to $825,000 - for four to five bedrooms, two to three bathrooms, updated kitchens and baths.
Thirtysomethings Ryan and Michelle McDermott are in their third house, but their first in Narberth.
They liked the area, especially its proximity to Center City, where they met and dated. But after looking at a dozen houses in nearby towns, it was "a Colonial on a cul-de-sac" that sold them on Narberth, says Ryan McDermott, a Comcast employee.
"It wasn't a hard decision," he says, noting that the previous owner, an architect, "added some nice flourishes." McDermott; his wife, a consultant who works in Radnor; and their three children, ages 6, 4, and 2, began calling Narberth home in June.
But obviously, not everyone here is a newcomer.
Drew Johnson has owned the Greeks restaurant on Haverford Avenue for 17 years. He describes the view out his window this way: "Strollers and dogs."
Dogs aren't allowed, and parents may worry about disruptive children, so Johnson had the idea of opening a craft-beer outlet next door to the Greeks.
"There has been a huge increase in foot traffic, and I've begun seeing a lot of new faces," he says. "Even though they're paying four or five bucks a can, it is like it's penny candy."
Offering advice to customers at Ricklin's Hardware is Tom Trolley, who has lived in Narberth for 40 years and was a borough police officer for 33.
"Tom knew everyone. He'd catch a couple of boys misbehaving, and as they ran away, he'd shout, 'Come back here, or I'll call your fathers,' and they'd stop in their tracks," recalls Paul Wilson, who has been buying buildings downtown and rehabbing them for small businesses since 1980.
Bill Martin has been borough manager for 30 years - "I'm still on probation" he says, chuckling.
"I've always had one goal, and that was to convince people that Narberth is one of the best places around," he says.
It seems to have worked.
"There is a New York stockbroker who comes back home for the Fourth of July," Martin says. "For the last 10 years, he comes to Narberth Park at 2 p.m. to help build the safety fence for the fireworks."
Narberth by the Numbers
Population: 4,282 (2010)
Median household income: $78,970 (2009)
Size: 0.49 square miles
Homes for sale: 17
Settlements in last three months: 8
Median days on market: 95
Median sale price (single-family): $407,000
Median sale price (all homes): $287,500
Housing stock: 1,700 registered properties, the majority built before World War II
School district: Lower Merion
SOURCES: Duffy Real Estate, Census Bureau, Eachtown.com, Narberth Borough
Contact Alan J. Heavens at 215-854-2472, firstname.lastname@example.org or @alheavens at Twitter.