You really need the 7518
For a router table you'll need the variable speeds. Since the diameter of you cutters will vary between 3" to 3/4" and require different speeds to operate efficiently and without burning.... So, if it's not the 7518 I would pass it by. You can get the cast iron Bench Dog Pro, huge table, or the cast iron tablesaw extension, a 7518 router motor only, and the Jessem Mast R lift, which I have for around $ 1000 more or less. Go for it.
I have the Bench Dog cast iron table saw extension, smaller table, with the above setup mounted on a welded table on casters, couldn't be more pleased...so I got another one! I'm still welding on that table tho...other priorites!
The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)