Velvia 100 has higher contrast, with less shadow and highlight detail, which can be washed out easier than other films i've used. I find Velvia 100 has a similar kind of saturation as the 50 speed, just a little cooler in the greens and yellows. I dislike Velvia 100 and prefer Velvia 50 over this film, except maybe a deep red sunset scene, which looks fantastic on the 100.
Velvia 100F has like you say more accurate color over Velvia 100, imho less cyan and more magenta and yellow in some shots, greens appear a muddy olive. Some say Velvia 100F is like a slightly more contrasty and saturated Provia 100F. I still have yet to find a place for this film, except for saturated portraits in a landscape setting.... but i keep shooting the odd roll.
I guess it will always depend on your own personal views and opinon at the end result, and the type of shots you intend to use the films for. A photography friend only uses Velvia 50 for everything he shoots.... to my utter dismay at times!