A lot about Velvia depends on exposing it in conditions for which it delivers results in aces and spaces e.g. pre-dawn, sunset/afterglow, and diffuse light scenes. I would not trust my rainforest imaging to any other film. Spot metering can get around the clumsy use of things like ND filters, and indeed spot metering is the best method to use in the absence of an onboard meter. But another thing is that many photographers will be naturally successful in getting the most out of Velvia, while others still may only be able to do that to a scene in B&W — how you see and interpret the scene. I am not a fan of seeing the world entirely in black and white for the sake of B&W.

I'm sure that if you are using medium format, you could get very large and visually striking print (A0, for example) to showcase Velvia. True, too, you could do the same from a well exposed B&W image, but whichever film you use will depend on the strength of your subject and the desire to showcase colour and hue — something B&W will never do. We do not live in a black and white world. Use your judgement to ascertain the best subjects for Velvia, get into the habit of using a tripod, long exposures and re-indexing (e.g. Velvia 50 and EI40 or EI32, but 'as is' for medium format).

At the time of writing this my lab is going through the first level LAB colourimetrics with a scan from Velvia with the output print at 81 x 51cm (printer maxed out). It will then be dibonded (aluminium plate hot-bonding). Got to now take down some other images in the gallery to make way for it in two weeks.