Standard box cutter utility knife with replaceable onesided blades has worked like a charm for me.
Otherwise I’d use a pocket knife or a non-stainless small kitchen knife if I wanted a 2 sided blade.
the w & t just looks so much nicer, and I do it 5 to 1 over cleft grafts. I don’t think the ‘take rate’ is much different. Actually the ‘saddle graft’ if done well also makes a nice graft without the scar tissue of the cleft grafts.
Top working an existing tree requires being creative in choice of graft.
Love my box cutter for grafts. The replacement blades are low cost and sharp enough to do a good job out of the box. So simple to put a new blade in wipe it off and graft until your tired. I rarely do large clefts and they would require a much bigger knife.
I am a novice grafter for sure, but I have gotten lucky with a few clefts that really healed cleanly with essentially no ugly scarring. So I guess it’s possible.
But definitely not the prettiest graft - no argument there.
Grafting horizontally will sometimes limit the growth. Sometimes I put a secure split at the graft union and then tie it slightly upward to promote more growth. This is a hard time of the year to get it growing again especially if it has already set fruit buds.