I recently ordered a TW multi charger and really like it. It does seem to make a transformer-ish humming sound (not loud but still audible) and some have complained about the short length of the cord (I keep mine on the counter so it's not an issue for me). Still, all in all, it's a nice gizmo. At the end of the night, I round up my spent 510
batteries, plug them in, and I have a full stash for
vaping the next day. I also have a few of their 'mega' 510/Titan batteries and so far, it's markedly reduced the need for frequent recharging. But the megas are big monsters. When you screw them in, the 510 isn't exactly a mini anymore. So I still like to alternate them with the original/smaller 510 batts. The multi charger gives me plenty of options because I can easily charge up a mixed group.
Watch for that sale in Dec and you can shave a few bucks off the cost.