Chojuro gets boosted by the clones and by all the other water characters and his standard attack can potentially hit 3 targets per round twice, applying so poison twice to them. If water enhancement doesn't hit him you have 4 characterd with +40% and if hits him you have him boosted by 80% + two more by 40%. Ao clones are there exactly to endure one hit that would otherwise kill him. In general no, sage naruto is not a better choice than chojuro in that team, bbecause if yoy fear mb blitz teams don't worry that also sage naruto would be killed by them if in front row, and if you meet many of them then just put ao in 1st prompt move and chojuro in 2nd. If ao dies is not a serious matter as far as you used in round1 his mystery (on that cute mb for example to prevent lightning armor if you have higher initiative or to hit him hardly so that doesn't get the boost of wb asuma).

EDIT: I just noticed you aren't running azure fang with that team... without azure fang that team is pretty bad since not only you don't boost chojuro and mei but you don't also apply poison and you neither heal chojuro! Of course you suffer hard defeats!