Love my Wista Field although it does have limitations. Nice and light, but not as rigid as say a monorail when stretched to it's limits. It will just about handle a 300mm lens, but can't get in close due to the lack of draw on the bellows. Both minor points as far as I'm concerned as the weight savings make up for it.
Lens wise, you would have to pry the Fujinon 135mm F/5.6 (Seiko shutter, lettering on the inside of the barrel) out of my cold dead hands with a pickaxe - A nice small lens that has plenty of room for movements and coupled with the Wista, does for much of what I currently shoot.