Barton prefers to trade in Legion territories versus NCR territories, saying that he finds it cheaper and safer. This is due to Caesar not demanding (or needing) heavy taxes from traders in his territory and the Legions effectiveness in keeping the trade routes secure from both raiders and creatures roaming the wastes. When asked about Legate Lanius, he mentions Lanius killing one of his brahmin just because it got in his way, though he goes on to say that he had sense enough to keep quiet and not seek reimbursement from Caesar.
If the Courier engages and is hostile with the Legion, Dale will still be neutral.
Once Dale reaches 41,000 in caps he will not dip below it while playing Caravan. Can be exploited to earn caps and get the Know When to Fold Them and Caravan Master achievements/trophies.
If the Courier is on bad terms with the Legion, Dale, instead of talking and just saying random quotes, will say quotes from typical NCR civilians. Even saying, "There's been reports of Legion raiding parties.", or mentioning Motor-Runner was put down. He will also offer no option to trade.
If Caesar has been killed, he'll ironically say that it "should be good for trade".
"Between having to hire protection and getting slapped with taxes, it's more profitable to stick to Arizona and New Mexico. But, I do cross the river from time to time when an opportunity comes along."
"Hell, I don't even need to travel with guards most of the time in Legion territory. All the bandits are dead or run off."