Tom,
Here's my, admittedly biased, opinion:
If weight and portability are an issue, the field camera may be the better choice.
Certainly, working with extreme movements with large lenses with lots of coverage is easier on a monorail camera. If you plan on working with lenses like the Schneider 72mm Super Angulon XL or similar very short focal-length lenses and utilizing all of their available coverage, then the monorail will be easier to deal with. (Think close interiors or close-quarters work outdoors with lots of movements needed.)
However, if you plan on using, say, a 90mm lens with lots of coverage and then shorter lenses using fewer movements, then you can accomplish all of what you need to do with a lighter-weight field camera.
You should be aware that you can add extra effective rise by simply pointing the camera up and then tilting both standards back parallel with each other. That, in conjunction with the available rise on the front standard of many field cameras, will give you more rise than you can use for lots of lenses, even the short focal-length, large-coverage lenses.
Here's a photo of my Wista SW, with the wide-angle bellows and a Wide Field Ektar 135mm lens with a 229mm image circle. I've used both front standard rise plus pointing the camera up and tilting the standards back parallel to get more effective front rise than I could get with the rise movement alone. I've also tilted the front standard a bit forward to position the plane of sharp focus where I wanted and I've used rear shift and swings on both standards to frame the image since the ideal camera position was not available. I used just about all of the coverage this great little lens has to offer. FWIW, the shot was a close-quarters outdoor architectural shot.
Hope this helps,
Doremus