Let's take an example,
Just ranked, 2000 max energy, 100 energy/hr charge rate, and 12000 xp to rank, a mission/activity with an 3.0 xp/energy ratio.

Inergon: 2200 energy instead = 6600 xp, 5400 left / (100*3) = 18 hrs
Human: 2000 energy = 6000+600 bonus xp = 6600 xp as well, 5400 left / (100*(3*1.10 bonus)) = 16.36 hours

It happens 18 / 16.36 = 1.1, the human xp multiplier. It takes 9% less time for the charged part waiting to rank. So human ranks better than inergon, particularly if you are waiting a long time to charge between ranks. However, you get 10% less actions (although you get 10% more xp for those actions), so it will take longer to finish missions (although, one might argue ranking a bit faster allows you to spend energy from the recharge faster to compensate).

The downside is miner isn't as good as builder, esp. at higher tech levels.

What do you think?

I've always wondered about this myself. I think if your doing missions/farming mobs for exp then human might be better, where as inergon would be better for pvp and still good for mobs/mission since pvp doesn't give that much exp and energy is always good for more actions. I have to admit though I could find much better racial bonuses for pvp, so when it comes down to it, it looks like you might have found the better racial bonus for ranking.

Edit: One thing you have to consider though- the Inergon bonus isn't going to do a lot for you when your waiting for your energy to recharge, the only time it realy benefits you is when your rank up or use a cube. The human buffs works anytime you spend energy for anything.

That's the main thing that I was proving above. I'm considering this very switch, although I wouldn't like to lose builder. There's also drannik, which gets about 40% more kill bonus XP from NPC effectively for the energy (and builder). Since I haven't maxed attack, it isn't quite as effective for me, but a hunter might get something like 10% more XP out of it. You have to be able to plow through flamehawks with some efficiency to do it.

For 90% of people that are not super energy heavy, charge makes up most of their energy and XP. In that case, human definitely wins. For energy heavy builds like mine, it's close but human still wins by a smaller margin. It takes a bit longer to run missions, but I guess the faster ranking basically makes up for it. I think XP bonuses also stack so when you pop both XP buffs you get 1.39 multiplier with human (1.265 with Inergon). Since I'm frequently running large energy with the buffs, it's actually not 10% but 12.6%.

Blah. had to change what I wrote.

I started at Vygoid Excavator, although it's better later on when you have a high production, the AP boost is helpful for the build.
I've already done all the high XP ratio missions, yet I could have gotten more XP out of them as human. Now that I'm unable to "power rank/multirank" anymore most of the time, it's different for me. The charge time as a % is similar (for example have 80-90% of next rank done after spending full bar), but as a number of hours I have to wait, it's increasing so the human bonus to it matters more to me now.