Hernadez.... Its a matter of different saws - really - Its all I can do to touch up the sharpness of a 16 tpi saw - adjusting the kerf is really hard. Thats why I would prefer a Japanese style saw - way harder teeth - keep their set better. The problem is you just do not know what the saw is going to cut. I don't believe tool supplier figures when given. So I stick for now with what I have - its cutting well and accurate.
I use coiled wire - don't try to straighten it. Nip it off as it is bent - and tap in from either end. You can buy flat wire if you want.
For hard ebony I widen the slots. Two ways really - firstly, they tend to widen if carefully re-cut. I often have to deepen as I radius my boards ( 48" ) only slight. Also - the board after mounting often needs scraping down a bit.
When generally sawing the first cut one tends to use the middle of the saw - so deepening the cuts with either bitter end - the kerf tends to be fresher ? Slight - but something - you can tell if its tight in the cut slot ?
Also - I contact adhesive together two sheets of 240 grit wet dry paper. Then cut a fresh edge - and use that side to side in each slot ( used dry ) Its just right for tight fit in my cut slot. I can then work the slot to be a good sliding fit with an 0.6 feeler guage. Not ideal - as one has to be very carefull not to widen the ends. Something short and stiff, with care, works ok (
Then my normal fret stock will go in ok on very hard ebony - but I also at times will file the tangs slightly both sides. I do that if the first seem too tight - and moreso on the frets past 14.
Its also helps to file the fret slot edges with either a fine triangular file - or better - a fine square file ( more obtuse corners) Helps the fret head to bed properly. Again - more important on ebony than rosewood.