Romeo is a good coach but this is a bad move for the Saints - not because Spags is any good, but arbitrarily moving to a 3-4 is a bad coaching decision by SP.
The Saints finally almost have the front 7 personnel they need for a 4-3, minus a DE & DT, and they are in range of getting a premier DE in the draft. DT isn't as bad as it has been and there are players coming up in free agency.
No matter what front the Saints run, they need 1, if not 2, safeties and unless Patrick Robinson makes huge strides, a starting corner ( even if he does, still need a nickle as JP hasn't done well ).
For a 3-4, Vilma and Loston just don't fit - they are sideline to sideline runners and not good at taking on blockers, so you need two new ILBers. Tez could play LOLB, but the fans that think Junior is any good simply don't know football; they guy just rushes up the field... over & over & over & over... easily flushed out of the play every time. In other words, he's a liability, despite what the dumbest fan base in the NFL think of him, so you need a ROLB, which luckily, you can get in this draft. Ellis or Bunkley could probably play RDE, but you may need a new guy there as well.
So to take a tally, you need 1+ safety, 1+ CB and either 2 DL or 3 LBers & maybe a DL. So 4 players in your 4-3 or 5-6 in a 3-4... not a hard choice. My guessis SP is over-reacting to failures to get a DT in free agency ( ie. it looks like they use PFF to sign people, bc they took Rodgers, Franklin, and Bunkley, and each one sucked - should teach them ), topped off with the failure that is Spags, plus envy in seeing other teams succeed, all adding up to a stupid, knee-jerk reaction.