True they don't last long in a mech but I still use and love my VTC 3's Don't quote me but if I remember right because they are what they are they have a slighty lower internal resistance than their vtc 4 brothers and even though I loose a few drags per battery...if I am sitting around the house what does it matter if I only get 20 puffs instead of 25? I have a pair I use in my Segelei 150 because I wanted to see if there was a power difference between 20, 25, and 30 amp continuous drain rated batteries...not how long they last but if the chip "stepped down" at high wattage to see if it could tell between the batteries....so far I haven't noticed a difference but I haven't built a coil I liked at above 110 and I actually get a good half a day out of them in the Segelei...a full day if I'm vaping light

I've got a pair of VTC 3's for my 30 amps, LG HB2's for my 25's, and Samsung 25R's for my 20 amp continuous batteries....so far at 110 they're all "feeling" like it's putting out the same...if I can't get to 150 with all of them or I feel like there's a difference like the chip "downsteps" because it thinks the batteries can't keep up I'll be sure to let everyone know.
As for efests....well....I've got nothing against them....I would just rather buy an authentic brand name battery for a buck more than buy a purple wrapper and see what "surprise" I get under the wrapper