I talked to Ralph by email with pretty much the same question. He said the BHI DSP is for reception and the 2.3 SSB filter or 500 CW filter are for both receive and transmit. I have the 2.3 SSB filter now and will soon add the BHI DSP inside the radio. Like another ham said go to www.w4rt.com
and listen to the examples there and then you can make a knowledgeable and informed choice.