"We doubt the rally will continue, but don't think the spread is likely to balloon," Higgins said. "Our forecast is that it will end next year at 315 basis points, as a gradually less accommodative Federal Reserve dulls investors' appetite for risk."
Others remain bullish on emerging market fixed income.
"The overall environment for yield-hunting remains quite favorable, in our view, reflecting the policy signals from both the Fed and the ECB," Societe Generale said in a note last week. But it added that it's being more selective.
"When adjusting for inflation, a number of local rates markets – in the long end— continue to show some value," it said, adding that any market producing a real yield above 3 percent would be "quite attractive" by this metric. The group includes Brazil, Hungary, Colombia, Romania and Poland, while Turkey and Chile look unattractive, the bank said.
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Societe Generale also expects bonds from emerging Europe will benefit from a "substitution" effect as euro zone peripheral assets begin to look overstretched.
Investors should also consider switching currency when looking at emerging market bonds, as euro-denominated papers should continue to outperform U.S.-dollar denominated ones, it said.
While the Fed is turning off the taps by tapering its asset purchases, euro zone monetary policy is likely to remain more accommodative, helping to support euro-denominated emerging market assets, it said.
—By CNBC.Com's Leslie Shaffer; Follow her on Twitter @LeslieShaffer1