The UVW 100 is basicly a one piece betacam sp camera, the guts block and chips are the same as a Sony D30 DXC camera, so it's a later model than the 507 two piece camera which is like a Sony BVW400 betacam sp camera head with a dockable 5 back, this camera is a tank! FIT chips, UVW 100 has IT chips, and is a lot lighter on the shoulder! also the 507 with the 5 back has two extra audio channels when you use sp tape, the UVW only two. Both these cameras make good pictures if set up right! the older 507 may have some bad caps or transport problems (age) I would go with the UVW100, but be sure to check out all operations on the camera are working, and you are getting a good recorded picture and sound.
The UVW 100 may have the option to shoot 16x9 and 4x3 you will have to check out the specs!