Johnny, welcome to the site and to the biggest problem that seat builders encounter. First black dye stinks, no matter what kind you use. It rubs off. So will most of the colors like the cordovan, red, blue, etc...... Still, Fiebings dye is the best. Oil or Alcohol based are about the same as far as I can tell..... Eco Flo belongs in the trash...best place for it. It is too fragile for bike seats. It will end up on the back of someone's jeans. Save the eco flo for coloring pictures that you hang on a wall, it doesn't belong on objects that you really use.
The best thing to hold dye in place (it still isn't perfect) is Neat Lac. You want to apply it with a cloth, don't spray or brush it on....it can get super glossy that way. One coat, maybe two at the most is what to use. However, it can be pretty shiney, so I've been recommending that you try what the old timers used back before Neat Lac was on the market. It is a wood finish called Deft. It is available in gloss, satin and flat. Again apply with a cloth don't spray or brush; one maybe two coats at most. Rub it in until it looks almost dry after you are done. You want to get this stuff IN the leather not laying on top of the leather. If you get Deft or Neat Lac on too thick it can crack and actually peal off.
I guess I should offer my appologies to Tandy here for hating their Eco Flo products..........nah they stink what can I say. This is of course just my personal opinion and should be taken for what you feel it is worth. There that was ALMOST an appology,.... right?
Dave