I just ordered a pair of Streak 4's and also NB1400. I also have a pair of Hyperspeed.
The Hyperspeed are definitely "one degree" lighter and more minimal than the other two. Of the three they are my favorite, but (big but) they have less cushioning, more than a tad, but not a huge amount. They have a great fit, are super light, and have the right mix of responsiveness & stiffness.
I ran in the NB1400 yesterday. They have a similarly good fit, but kind of a funny toe box and annoyingly short shoe laces. The cushioning is nice though. They are still light weight but they offer a tad more cushoining underfoot. They aren't quite as responsive as the hyperspeed.
I briefly ran 100m or so in the Streak 4's. These shoes are really stiff. They have a big chunk of plastic in the mid foot and don't flex laterally. They also have a significantly higher heel to toe drop. They are fairly firm, but still offer protection which is nice. Definitely would be responsive and fast. In essence, they are the perfect marathon shoe for a neutral, heel foot striker, who also likes firm shoes. Given the lack of flex and heel to toe drop, they are a very different shoe than the Lunaracer. If you like the Lunaracer, I don't see why you would like the Streak. There's nothing the same about them, except for maybe the lack of support/control, and the brand...
Side by side comparison for you:
Lunaracer is soft, Streak is firm
Lunaracer has a lot of flex, Streak does not
Lunaracer = no plastic in sole, Streak plastic under arch
Lunaracer moderate heel to toe drop, Streak the highest of any flat I've worn.
A couple side notes to help narrow down:
I've had a pair of A4s and in my opinion the A4 and the Hyperspeed are almost the same shoe. So you can just lump those two together for decision making.
Stay away from the fastwitch, if you need a 100% neutral shoe.
People I know have liked the racer boost shoe. A lot of trained in many of the above shoes as well and liked the boost more.
Last question, what minimalist/lightweight shoe are you currently training in? That would also be a good start in terms of picking a shoe to race in.