There's a whole huge list of people better than Aries who should be brought in. Danielson, McGuiness, Claudio Castagnoli, the Briscoes. You are right that they can't have two Samoan gimmick guys together though, especially with such different variations and styles. The options would be to repackage Umaga/Jamal again, or to just call Joe by his full name, seeing as Joe Seanoa is a pretty good name really.
I think the Briscoe's will eventually end up in WWE. Danielson, not too sure, but if they brought him in and used him right (how likely is that?), he could be a huge star. Same with McGuiness.
WWE thinking would probably be to bring Joe in and throw him right in a feud with Umaga. Quote me on that, actually. I'm pretty sure it'll happen if they're both in the company at some point in the next years.
Whoever pitched the WWE CM Punk heel idea, I'm in definite agreement with.