Glad you asked.
The 1400 is my go-to, for tempos and racing 10k to the marathon. I'll also use the 890 for recovery or long runs sometimes, feeling like it might save some wear on the calves and Achilles.
I train with a guy who knows and runs in the NB line, who put it that he wouldn't race a marathon in the 1400, but the 1500 he would consider. A bit more support but not quite the (relative) cushion of the 890. Sounds great.
For me, though, the feel of the medial post is a bit annoying, even after many miles to get used to it. Strangely, I also seem to get a hot spot under the lacing, with some extensor tendonitis before I reconfigured them Lydiard-style. (This is an issue I've never had in my life with any shoe.)
Personally, I'll stay with the 1400, Brooks T#, Adizero Boston/Adios/Tempo. Interested to hear what others have found.