From a guy who owns and regularly uses an IPro, a Buzz, a ProVari, and a Lavatube:
YMMV, but 5.5 - 6 volts won't be missed. I rarerely go much past the red mark on my NotCigs devices, and have yet to find a juice/carto combo that demanded more.
Battery metering, which I figured would be a plus, is actually just one more thing to worry about. It's part of my morning routine to change the batts in whatever I was using the day before, and it is extremely rare for me to ever run out of battery power. Nevertheless, when I am using a device that can check battery capacity, I feel compelled to check occassionally. When I'm using one without, I never even think about it, and just enjoy vaping.
Atomizer ohm testing - look, my LCD screen says the same thing the box says. Neat trick!
Not knowing what voltage you're vaping it - not really true. Numbers are just one scale to measure by. Maybe it's my preference for the IPro that causes this, but I have my voltages memorized on my favorite carto/juice combos as "quarter-past yellow" and "just shy of red" rather than as 4.4 or whatever.
I don't have an all day vape either. Right now I have 7 different tanks filled with 7 different flavors, with an additional 4 more flavors loaded into random cartos - I'm ready to vape whatever tickles my fancy at any given moment. While the accusations of the ProVari menu making it slow to change settings are greatly exaggerated, the wheel is still more convenient.
In short, I think you'll be very happy with your IPro.