Both Weller (for the TCP series) and Hakko recommend against filing the tips as it removes the plating that will take solder (tinnable plating) I wonder if the abrasive does the same thing.
That being said I will try the Ersin product.
They, in my not so humble opinion make the best lead tin solder (really the flux I think) I have ever used (it was also the first solder I used...
When I was 14 I passed my Mil Spec soldering test and that was the solder used so more likely than anything else it is a sentimental thing.
As to the "Brass" cleaner by Hakko, one came with the iron and I love it, I have both and distilled water for the sponge as well (prevents lime from building up on the sponge and they last about 5 times as long).
The "Brass Cleaner" seems to do as good a job as the sponge and it 'keeps' the residue trapped... no solder balls and crumbs to be cleaned from the work place.
Doc