If you are doing contesting, the CW Filters will help. I use the FT-980 during contests, and the narrow filter certainly helps with strong adjacent signals: it isn't as good as a selectable narrow roofing filter (like the FT-DX101), as long as the nearby signal doesn't desensitize the receiver it can clean the audio. That being said, you can still do a lot with the APF feature, and the notch ... even though these are still in the audio portion instead of the RF portion of the signal chain.
The FT-980 is one of the first production rigs with a "roofing filter" ... back before they were called roofing filters. This was likely directly influenced by Bob Sherwood's experimental work with the Drake 4-Line (adding a roofing filter). The fixed 15-Khz 6-Pole really helps with non-adjacent strong signals. The biggest issue with this architecture (my opinion) is that since it is a VHF up-conversion first-IF (at 47.055MHz), it was hard to get anything narrower than 15kHz, and the skirts fall off less sharply (by Hz, not decade) than a lower-frequency down-conversion filter.? And of course ... this was a loooong time before electronically selectable roofing filters :)
Note: In-rad offers a better XF-1001 replacement (supposedly): details can be found in the files section. But ... it is pricey.
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-Mat Breton, N8TW
Mat Breton N8TW