About 6 years after trying the G-2 for the first time, I feel it's time to write a 2nd review of it.
As of now, I think that the G-2 is the pen family that allows the most customization, since you can choose
a)4 different body styles and sizes
b)4 different tip sizes
c)many different colors (not available in all sizes)
plus, you can fit cartridges designed for
a)Q-7 (0.5mm gel)
b) Precise Vx RT (5mm, 5mm liquid)
c)VBall RT (EF, F, B, liquid)
d) Mont Blanc Rollerball (Fine, Extra Fine, liquid)
I decided to stick with the 0.7mm regular G-2, which has the most colors available and I find it to be the best in most types of paper.
You can feel how the pen moves freely on the paper, doesn't feel scratchy or anything like that, the ink is not dispatched in excess, however, you still need to be careful not to smear the ink. The ink seems to be lasting, although the amount of writing I do now is by no means comparable to what I was doing a little over a year ago.
My main complaint is the availability, some colors like navy blue are only available by the unit from Pilot's website, the other option is a 3-pack available at certain stores (it comes in orange, forest green and navy), which sometimes complicates things, since I don't use forest green a lot (let alone neon orange).
And for those who try the MontBlanc conversion, DO NOT carry that pen in your pocket, that ink has a nasty habit to spill when you accidentaly press the clicky mechanism.