This is a easy choice. The color pro lens is of better quality. The 670 gives you the negative carrier, easel and you can use the dichro filters vs buying a contrast filter set. I have a 670 and it's column is more stable than the 6700. The 670 base board is a few inches larger and will be appreciated with enlargements of 8x12 or larger. My bet is not many prints will be made over 8x10 but if you need to the larger baseboard is nice.

I would not recommend doing chemical color. However, B&W is simple and silver fiber prints can look nicer than digital.

670 Disadvantages:

The LPL 670 is larger and heavier (10 or 15 lbs) than the 6700. The transformer is an additional 10 lbs. Not a big consideration.

6700 Disadvantage:

Smaller baseboard, not as sturdy as 670, does not have tilts on the head, may not be a diffused light source which helps suppress dust, largest negative size 6x6, has a poor quality lens for not optimized for 35mm, and is not complete with carriers.