Depends on the constituents of the debt fund. Recently,
JP Morgan's debt fund took a big hit due to Amtek Auto's default on debt payments. Just look at D/E ratios of the constituents. If the ratios of the individual companies is high as compared to their respective industries, that should ring bells. You can also look at their default/payment history.
Corporate debt funds should give a higher yield than FDs, but highly likely that they wont be tax exempt. You should be looking at after tax returns to compare them. GSec based funds should be almost equal to or slightly less than FD's return.
I handled treasury of an Indian company for a very short period (didn't decide on where to put, just followed the process in place). Some of it was in risk free debt funds. Tax exempt yield was 5.9%-6.0%. The remainder was in FDs, with a before tax yield of 9.0%-9.5% (as far as I can recall), which was slightly higher than the debt fund. But debt funds give you the option of liquidity, which is not there in FD. So, higher price (lower yield) of the debt fund is the value of this option on liquidity.
Regarding Credit Opportunities Funds,
this writer thinks it's not a good deal. You will be exposed to credit risk, as is the Amtek's case.
PS :
I have personally never invested in one, but just sharing some opinions, which, oddly enough, violates my signature. Just thought maybe can give some pointers since nobody replied.