WIDESPREAD PANIC AT TIME WARNER CABLE ARENA: The jam-band road warriors of Widespread Panic often fall prey to expectations raised by their own 19-year legacy. At its best, WP merges The Band’s sepia-toned authenticity with the Allmans’ bluesy swing and those rare, through-the-looking-glass moments when the Grateful Dead pulled the rug out from under you. At its worst, the long-running Athens, Ga., crew approximates the Dead’s more frequent gassy bloat with meandering jams that vanish up the band’s collective ass. Despite losing founder Michael Houser to cancer in 2002, Widespread Panic has soldiered on, recruiting N.C. native Jimmy Herring for the lead guitar spot in 2004. After playing Charlotte for a NYE party last year, these seasoned jam-vets flipped the script, going acoustic for a short winter tour before taking a long-overdue hiatus. Breaking their 10-month silence, the revered (and sometimes reviled) stalwarts play two gigs. On December 30, there’s a sold-out fund-raiser for Tunes for Tots at the Fillmore. The next night, they’ll ring in 2013 at Time Warner Cable Arena.