[tspiteri]

It depends on what you are doing. There are tools in the Xilinx tool set enabling you to design filters or other things in MATLAB Simulink, which are very convenient. But if you want to write a processor, however small, you cannot really do that well. Because the hard part is getting a good design with proper timing and synchronization between different parts. I think it's harder to get such a good design using MATLAB/C to HDL tools than it is designing directly in HDL.