I own both and i can say this.. For the price, Neither can be beat!
The IGO-L and IGO-W are awesome RDA's. My only issue with them is they are a little thin and the metal heats up really quick. The build quality on the Nimbus, is thicker and built a little better. I am not a fan of polished/chrome looking stuff, So the IGO i dont mind sanding down to a satin/raw stainless .. The Nimbus on the other hand, Which i could sand down, Would totally destroy the looks of the Nimbus design ( plus decrease its resale value )
I usually only build single coils, and i prefer the space and juice well on the Nimbus.
The post screws though on both? To me? Almost seem the same quality ( which is rather odd seeing there price difference )
and vapor production? Is or can be the same on both.. Its a matter of drilling the right sized holes and building the right coil. So that isnt a issue.
What i did was i bought a IGO-L ( or W ) and tried that for awhile and decided if i was going to stick to RDAs, then i would upgrade to a Nimbus which i did.
My only negative about the Nimbus is the polished look ( which is a matter of taste ) and the cheap post screws used.
They are both well worth there asking prices