I think that's a good choice. I have the 7670 and like it a lot. Set up can be tedious but it cuts a very clean dado. You should measure your "standard" dado widths because my 3/8" was slightly narrow (.01" if I recall correctly) so I had to shim to get to precisely 3/8". Of course you could also tweak the key width to match the dado. You will want precision on that because even after just a couple of pins the errors added up to a way too tight fit.
That said, I use my router table for box joints. My bits are spot on 1/2", 3/8" and 1/4" Setup time is a lot faster though the table saw, once set up, is fairly quick. I think the router table, all things considered, is still a bit quicker. I have great dust collection on my router table so it's also cleaner than the TS.