Good question. You definitely want 1/2" shank capability, which would argue for the 1400 over the 1010. The question is whether you wanted to expand your capabilities even further by looking into an even heavier duty model (3.25-3.5HP) from another manufacturer for a dedicated under the table router (like a Triton or a PC), and then use the Festool purchase to get something like the 1010, which I think is, pound for pound, a more versatile machine than the 1400 (through the edging plate for example, which gives you horizontal routing capabilities -- edging plate also works on 1400, but is more cumbersome).
I don't use my 1400 all that frequently anymore after I got the 2200, which covers the heavy duty tasks (that I'm not doing on my table mounted Triton), and for lighter duty stuff I prefer to reach for the 1010. It's really only when I need 1/2" capability and I'm working on a surface where the footprint of the 2200 is too large. The 1400 is still a great router, though.
Note that template routing is probably better on the 1400 as well, due to the difficulty of centering the ring on the 1010 (unless you buy an aftermarket template insert, like the one from Leigh).
Another feature where the 1400 excels over the 1010 is the edge guide. The 1010 edge guide has fixed rods, whereas the one on the 1400 are detachable. This means you can swap in, for example, your own set of longer rods if you ever have the need to rout parallel to the edge over long distances.