500 Hz filter for IC-735

[Howard Lester]

I need to know whether the 500 Hz filter is worth buying for the Icom 735.
I use CW about 80 - 90% of the time, and I want to improve the selectivity
over what is available from the use of the Passband Tuning control alone.
Since I have no way of "testing" the filter other than by BUYING it, could
someone who has one please do the following and let me know the results:

Set the Passband Tuning Control fully counterclockwise and listen for a CW
signal that has some surrounding QRM. (This setting of the PBT is, according
to the manual, 800 Hz bandwidth, but the skirt shape is unknown.) Now,
switch in the 500 Hz filter. Any improvement? If any, how much?

Thanks for any information.

Howard KE7QJ    hlester at as.arizona.edu