I have a H4L NV and I have to say it is absolutely fantastic. I also have an Affinity Carbine. There is nothing between them performance wise. The carbine has no concaving, the NV has minimal concaving. The handle on the NV for me feels more comfortable as it is slightly thinner (I have small hands and use youth size gloves).
The customer service I experienced from H4L when I had the NV re-handled was excellent and their workmanship top drawer. Personally I believe all of the top makers (aldred, red ink, h4l, RK, b3.....) do excellent work so whatever choice you make you should end up with a good bat.