I've had some small experience with the Crown RBA but I can't address the OP's question; No experience with nichrome. Just wanted to volunteer (IIRC), it'll come with a prebuilt (I think it's steel) 0.50 ohm coil installed. I've also rolled my own kanthal. I like the RBA. it's little and limited to a single coil, but it works well in that quality tank. Won't have air the airflow of the factory pre-built coils - but so what.
It's easy to build coils the challenge is wicking it. Wicked properly you can even top fill, but it still might leak. Wicked properly and bottom re-filled, it shouldn't leak at all. Just thought I'd pass this on fwiw.