My own experience. I've only used perhaps a dozen Boges for my shorter cartotanks. Pretty nondescript with them.
The majority of my tanks are larger and require the XL cartos. For months I used the Smoktech dual coils in 1.5 and 2.0 ohm resistances. To me the lower resistance was too harsh. With the 2.o ohm standard resistance it was nicer, but I still occassionally recognized some burnt taste.
That's when I started investigating single coil cartos. From what I could find, the dual cartos were designed for more vapor production for 3.7v devices. But I also read that to get the most potential out of both coils you had to push 4.5v minimum into them.
I'd read good reviews of the single coils, so I ordered a bunch from Smoktek.
(Note the spelling, different companies?) I changed out all of a dozen tanks with brand new pre-drilled 2.0 ohm single coils. I got the same flavor and vapor production, more battery time between charges, and in over 2 months of changing over, not one incidence of burnt taste.
I just got a batch of 3.0 ohm 2-holed single coils to use on my Provari and these are performing excellently also.
http://www.smoktek.com/Single-Coil-XL-Tank-Cartomizer-for-the-SmokTank-XL_p_211.html