while I see why you would select him there is one troubling thing that you overlook
Vatuvei and Maumalo play the same position - Left Wing
Neither is a 'right sided player' if you look at their running style, ball carrying arm etc
in addition... two defensively inept, cumbersome giants on the wing would do my head in...
For me it is one or the other
In defense of Maumalo he's been working hard on his defensive issues this season and looks to have made some improvement in that area. He's played a lot of his career as a back rower and we've also seen him on the right wing be effective carrying the ball in either hand, if he was an out an out left winger like Manu I could understand him being pigeon holed to that position. I think he'd be fine outside Ayshford and he's a far better option than Jonno Wright in attack.
I'm nervous in defense whenever Manu plays as I'm sure we all are but I think Maumalo's improved in that area since he made his debut.