Marksman Building?

Question: Are crimson guardians effective at 120, assuming enough hp to take a hit from anything other than the mace attack? Compare it to typhons, newties (solo or party, but not with an ultimate-spammer), or anything else that might have a chance to compete in terms of experience rate.

I couldn't start that early, so I'm taking somewhat of a guess that it would depend on your equips.

typhons: I never trained at them.
newties: solo sucks by the time you're 4th job. At 128 when I moved to guardians, I started getting more exp than in a 3 attacker party. unless the other 2 members of the party were 14x+ but that doesn't happen very often.
if you have the hp to take a hit at 120, then give them a try and time your exp. it should at least be comparable to a party at newties and you don't have to go through the trouble of finding 3 other people.

you probably want to start trying guardians while you have no exp to loose. I died about 5 times in 6% getting the training method down.