If you get one that puts out a true 3.7v loaded voltage, it will make a BIG difference over 3.2v, especially if you use a low resistance atomizer. My personal problem with 5v mods is that not all liquids taste as good at 5v. Once you get a taste for high voltage vaping, you will want to be able to dial up or down to find the sweet spot for each liquid you vape.
It's kindof a slippery slope. As long as you are using 3.7v and you enjoy it, it's awesome, but if you ever go high voltage... you will inevitably go vv.
EDIT: nite street
I don't know yet I have a tornado-t that I'm not happy with.I want a good solid,versatile mod.TAT suggested an empire.I was looking at a glv3 also.But the buzz pro has caught my eye also.To tell you the truth I'm not sold on a vv mod just yet.I'm still trying to figure out if I want a 3.7 or 5 volt mod.The 3.2 volt tornado that I have is almost right but it isn't.I'm just trying to figure out if 3.7 will make that much of a difference or if the jump to 5 volt will.