As i recall, the M390 Barrage is a dealer exclusive and not a new version. The 154CM version is the one sold everywhere else.
Its a different model number (581) but not an exclusive. You can get the m390 model anywhere.
My opinion:
I think the barrage is better for most tasks I use a knife for but if you need a thick, heavy blade for what you do, the zt would be better suited. I personally like thinner slices more than heavy tank blades but a lot of people are the other way.
The barrage is spring assisted which I dont mind (would prefer it not assisted) but its a deal breaker for some people who hate assisted openers.
Steel wise, I like s30v (and I assume s35 which is supposed to be the same) better but some people say that once you reach a certain level of steel, it makes no practical difference. I just dont like 154cm much myself for some reason (I might be biased due to horrible leatherman 154cm which was my first use of this steel). A 581 with m390 steel is still under your price limit though.
For build quality, most people would say zt is better but I think that benchmade gets a bad rap due to mechanics of axis lock knives and not because they're poorly made or flawed in some meaningful way. Its harder to adjust axis locks (particularly the barrage with the covered pivot) so its more difficult to get the blade centred or to find the sweet spot of no side to side play vs quick opening.
Benchmade and Kershaw both are known for having exceptional warranties and service. Ive never had to send a knife for service to either company so this is just word of mouth but both companies often get praised for customer care.
Basically, if your set on the 580 (unwilling to consider the 581 - better looks and steel), Id say the zt is probably a better knife overall. Id still rather have the 580 for edc though because of my dislike of tank folders for common tasks. If you want a sturdier blade or the sold feel a slab of titanium gives you, the 550 your knife.
PS - also keep in mind that the thwack of the barrage opening has a tendency to freak some people out. Its pretty loud and abrupt so I can understand why it would be disconcerting if you flipped it out to cut the straps on a box of paper in the office. The zt is pretty aggressive looking as well though so it would give you same problem without the noise to draw attention.