First: there is nothing truly consistent in
vaping when going from one to another, reason being too many variables.
With that being said, if you have a good carto with the filler you should have a good carto modded. Basicly if you have a coil that heats up and you get your juice to hit it you are gold
When I was first introduced to this,by a member dogsbody, he was putting 10+ drops in an original KR808 cartomizer. He was relying on the center post of the carto to hold the liquid with out leaks(one inconsistancy

). Since it takes a bit to balance the dripping between ("too dry" to "too much")
How long will they last? My low average is 1mo, but that is depending on the juice I use and how the coil gets gunked.
My personal preference is not to go over 5 drips, I mean the purpose is to treat it as an atty.
Most of my experience with this is with the old Kr8's and just recently with the vertical coils like the bloog. I can tell you this any model with a vertical coil one should have no problems modding. Now for the horizontal ones.. these days suppliers are 'customizing' them so much it's hard to rate difficulty level, but with patience I would imagine none would be too hard to mod this way (with the exception of cartos with 'glued' top caps)
Hopefully I shined a little light to what you were pondering on.
LGD