Disclaimer: I'm a relative noob. Vets can feel free to point out my technical inadequacies.
I understand the theory, but in practice I haven't experienced the "lower ohm coils drain batts faster". In fact it's been the opposite, because the 1.5 coils vape better at lower voltage than the 2's.
The upgraded ("capped") 1.5 coils are for me much better performers than the old style 2.0's. They also last a lot longer. The 1.5 that came with my Aerotank vaped reliably through 30 mls of 'Apple-Cinnamon' at 3.6(!) volts before any noticeable performance decline surfaced. (Side note: this same liquid 'murdered' 2 Aspire 1.8's within 24 hours.) Cleaning and incrementally bumping up the v has gotten it through another 10 ml, but its definitely past its prime now.
(In my relative newbie experience) I can't get satisfactory performance from the 1.8 and 2.0 Kangers at anything under 4 volts, and 4.5 is more the norm. With the higher ohm coils, it seems like I'm always in a vicious cycle of cranking up the volts to sacrifice flavor for vapor. Hence, I'd recommend the 1.5's for those using equipment limited to 11 watts (IE: batts up to and including MVP 2's). At 3.6 v, I can get the hit counter on my MVP 2 well into the 900's before going yellow. At 4.5 volts it's more like 650 hits.
Also, with the airflow wide open on my Aerotank, I get occasional dry hits with the 2.0 coils. The 1.5's don't do this. I have no idea why, (maybe it's just my imagination) but high airflow and high ohm Kangers don't mix well for me. I don't use Protanks, but the 2.0's work very well in my EVODS, so that's where I use them.
Cons: The new 1.5's, especially in a mini Aerotank, are the antichrist if you worship stealth vaping. They snap, crackle and pop like a badly tuned 125 cc motorcycle, especially during their 'break in' period. Normally I enjoy the sounds, but it's a bit unhelpful when I'm trying to vape sneakily in the bathroom stall at work.
They definitely seem to be juice hogs compared to the 2's, but that's offset by their better performance.
I haven't figured out a way to disassemble them without A) breaking something or B) destroying the coils in the process. About all you can do to clean them is soak them in (whatever) and hope for the best (unless the idea of blind dry-burning appeals to you). I like the old style coils because you can just pop off the chimney and have instant access to the coils. Also, I haven't tried to rebuild a new one yet, but it definitely looks like it's going to be more of a hassle.
I think that, when I find a coil that can get through 50 mls of juice before any noticeable performance drop, I'll stop bothering to rebuild them. The new Kanger 1.5s come close.
jambi