I would be in favor of bringing in Carter if the other pieces made it worth while. I think Carter is underrated overall because he didn't end up being as good as the hype of the next Jordan. He's also lacked teams success, but, frankly, he's had as much team success as Jason Kidd, yet Kidd doesn't get the "loser" label, somehow.
Anyway, I think a deal for both sides would be:
Ray plus Giddens and Pruitt (or Tony or Scal if they prefer, but Giddens&Pruitt would save them the most money)
for
Carter, Najera, Dooling and Boone.
NJ saves 4.5 right away, as well as 23 mil the following year.
For Boston, Boone is a solid extra big body with legit size, Najera might provide some hustle but is really financial incentive for NJ, Dooling is a legit backup guard who is a defensive standout, and Carter fills in for Ray. Additionally, Carter would have a team option the same year Pierce and Dooling comes off the books, so the C's would have 42 million coming off the books at the same time in that offseason just between those three players:
Rondo/Dooling
Carter/Eddie
Pierce/Walker/Tony
KG/Baby or MLE
Perk/Boone