3.7v isn't, IMO, good for some juices. I use Riva 510 (3.7v) and Ego (3.2v) batts with the mega attys, both
tank and filler cart type. Some juices taste better at 3.2v on a standard atty and others are better on 3.7v. Just an observation. You might find that some juices have a burnt edge at 3.7v.
I guess what I'm saying is that you are better off with a system that lets you pick between the voltages to adjust the taste depending on the
juice.