Thoughts on Unlimited Barbarian Exp?

This was a mod I got pretty early on because it always frustrated me that my units would stop getting experience from barbarians after 2 levels. However, I've found that having the ability to farm barbarians for experience is also incredibly exploitable.

If I'm playing a military campaign, I can almost always be guaranteed to have lvl 3 units (so completely specialized in either flat or rough terrain or, more likely, medic upgrades plus specialization) by the time I'm ready to attack my first city. If I've got 2 warriors, 2 spearmen, and 2 archers I'll have some ridiculously powerful units by the time I've taken out my first civ (my archers will all have 2 attacks a round and my warriors/spearmen will have march). Once you've got those upgrades, taking out further civs becomes ridiculously easy (even on immortal difficulty). Throw in just one siege unit and the early cities with 25+ defense don't stand a chance.

By the time you're starting to feel a tech crunch against the better opponents, you've already taken over 5 other civs (assuming you raze all their cities except the capitals/cities with wonders/holy cities).

Now, to be fair, you can do this without farming barbarians as well, it just helps to shotgun you into military dominance faster. So what do you all think? Is it too much of an exploit to continue gaining experience from barbarians?