texas instruments dsp 54xx
You have also to consider that TI produces high performances devices, like the C6x series, capable of high speed (the C6455 runs up to 1.2 GHz clock frequency) which can perform simultaneously tasks normally reserved to GPP processors (control flow, device interface and so on) and DSP operations (MAC, FFT etc.).
Of course such devices are not the cheapest, but you should consider the total saving in the BOL (bill of material) you obtain by substituting several devices (GPP/MCU + low-end DSPs used as co-processors) with one device.
Obviously you always have to evaluate the target application before making such a choice: just think that changing the platform implies that you should do a porting of all your SW to another environment and in case of DSP this could mean rewriting almost all the optimized assembly routines obtained after months/years spent debugging!
Regards
Mowgli