A sweet-tempered program of old favorites? That's what the Curtis Chamber Orchestra appeared to have in store for its Philadelphia Chamber Music Society concert on Friday. But the program was actually a musical minefield - pieces much loved on recordings but rarely slotted comfortably into concerts with limited rehearsal.

Surely, Copland's Appalachian Spring couldn't fall into that category, could it? Yes - the suite that was played at the Kimmel Center's Perelman Theater was in the original orchestration for 13 instruments, created when the composer was still calling the piece Ballet for Martha (as in Graham). Everybody pulls much weight; there's no place to hide. And though the concert was mainly a guest appearance by conductor Giancarlo Guerrero, the Copland was bravely led by Curtis conducting fellow Edward Poll.

The benefit of this choice was a break from the familiar warm-bath orchestration that masks the modernity behind the folksiness. Friday's performance showed that Copland wasn't turning his back on his knottier earlier music but rather accommodating the rhythmic needs of dancers, incorporating the Shaker hymn "Simple Gifts," and not letting the music's many moving parts wander too far in opposite directions.

It was a performance that could restore your faith in the piece, with none of the tentativeness associated with still-in-conservatory conductors. No surprise after glancing at Poll's credentials: The Bryn Mawr native was assistant conductor at the 2014 Glimmerglass Festival, and, as a composer, is working on his second opera.

The Guerrero portion of the program revealed the challenges of Bernstein's Serenade and Stravinsky's Pulcinella if only because they weren't entirely met. The suite from Stravinsky's breezy, neo-baroque comedia dell'arte ballet sounds chic and amiable when well played, but pushes every section of the orchestra with all manner of chamber music-like interludes that require much more than technical professionalism. I've heard major orchestras come to grief on this one. In the early movements, Guerrero took cautious tempos. Halfway through, some Mediterranean fire set in, causing a bit of audible labor - though the performance became far more interesting.

Bernstein's violin concerto is one of his best pieces - tuneful, high-spirited, jazzy, and utterly treacherous, starting with built-in balance problems. The harp is important, and must be heard. The performance's main deficit was humor and wit: Bulgarian violinist Bella Hristova, a 2010 Curtis graduate, missed those elements completely and only really seemed to enter into the piece's spirit in the heartfelt fourth movement.

This is not to discourage such endeavors. After all, perhaps it is only under the Curtis Institute's greenhouse circumstances that we may someday hope to hear Bernstein's neglected masterpiece, Songfest.