As everyone knows there's a big difference between the 3.7v on cig style ecigs and the 3.7v on mods and it's all about peak voltage of 4.19v - where some batteries are running on that for longer periods. The regular 510 batts, eg. I don't think even make it to peak - the difference between a newly charged reg. batt and the 14500, for example, is extreme. It is even a significant difference between the 14400 and the 14500, imo.
After having used the Protege via PT at 5volts for over a week now, I prefer the 14500 batt + Joye 510 atty combination. It doesn't take long on 5V to begin tasting the 'dry atty' taste - it eats liquid and for me, with the exception of one coffee flavor, all other flavors taste better on the 14500/510 combo than on the 5V with any atty and I've tried the 510, 510HV, 901, 801 and cartos.
Also while the 5V does produce a bit more vapor than the 14500/510 combo, I don't find that as big a factor as flavor - the vapor is sufficient and probably more like a cigarette where the 5v is more like a cigar as far as vapor goes. I should note that 'throat hit' isn't a big consideration for me - although it isn't zero consideration - with the 14500/510 I can feel the vapor well. With the 5V it can be irritating.
I'm glad I tried the 5v and it is interesting, but I think I found my best combination at 3.7/4.2Vpeak with the 14500/900mAh and the Joye 510 atty for flavor, vapor, the throat hit I want, and the size of devices that deliver it - Bartleby and Protege - which will last me 6-8 hours before need for a recharge. I have no need for a battery that will last 2-3 days. I also have a Chameleon that also gets the peak 4.2V with a different battery at a slightly lower mAh.
Hope this helps someone....