I took my tank emblems off with fishing line last year.
there were some very slight marks on the paint form the line/grit.
I sawed up and down as recommended. "BUT"
I would say to pull the line from the bottom to the top.
I figure that there is more grit lying on the top side of the adhesive than there is on the bottom and you might as well keep the line as clean and grit free as possibble while it slides across your paint.
Fishing line is cheap one pass is all you want to use it for.
I still used just a small portion of the spool.
Good Luck
I preffer the no emblem names anywhere, look.
Since I've heard a few stories about scratching the paint with fishing line I opted for this method.
Run the tank low on fuel, if you don't the tank will never get hot enough to release the bond.
Apply heat with a good hair dryer to the emplem
with a soft plastic scraper ( i used a bondo spreader) lift the emblem slowly letting the heat release the bond.
Take care not to pry so hard on one side that the emblem digs into the paint on the other side.