Update on my B's - got my Joye B heads and holders from Heaven Gifts today - 4 days shipping!! That's been much faster than say last year... last orders have come in within 5 days.
I got some 'upgrade' batts and PT's - work as you might expect - you can tell the difference between the high mode and the constant mode (3.3v)- I vaped the first new B dry without a leak or burning - vaping DV's Ylang Ylang - VG with VG nic base. Great flavor! I grabbed an old t tank with the soft cap - no stoppage of airflow that I got with the Ovale B on the soft cap - but the Ovale vapes well with the hard cap - just still getting some leakage in less than a quarter of a tank about 50% of the time, even after a vodka cleaning? It may be an odd one - haven't tried other Ovale heads yet.
The heads appear to be the same - joyetech with a larger B and Ovale with a B - the A lr's I have are marked "LR" as well, but those are A's. The Ovale metered out at @2.4Ω. The one Joye I have running is at 2.3-2.4Ω going from one to the other and back
My joye T attys came in around 2.1 to 2.3Ω - but most in the 2.1-2.2 range - might be why the t's tend to burn some juices and the c's don't?? I'm thinking the conductivity of the spike is part of it because with the eGo mega's - with cartridge/filler, I was vaping the LR's that came in at 1.5Ω on the meter without any of the burning I experienced with the T's. Not as close of contact with the coil and the mesh wouldn't transfer the heat like a solid spike would. So... perhaps the .1 or .2Ω difference is not affecting the spike in the c's as much as the t's. Wouldn't think that would do it, but it's my best answer at this point.
BTW, as a side note, speaking of the megas and earlier - I have about three old eGo batts that are really about to croak. Originally black, now shining stainless

- absinthe is bad on black coatings

They're not holding charge like they used to and for the first time I've experienced where the led on the button grows dim and fades away (these don't have 'cutoffs'

... next hit it's back but if you hold onto it, it will fade. I've never experienced that - I've 'blown out' batts on lrs or from 'dry burning' but never really had one 'run out' on me - this being close to three years of vaping! Again, I have several PV's going so the mAhs and total time for batts are 'split up'.
I'm on my second tank - about 1/4 down from full - no problems... and I've been power vaping it mostly. So far so good on the Joye B eGo-c's.