Never used the edging setup for the 1400, but I've seen some comments that it is a bit unwieldy if you are doing things like trimming edge banding.
The advantage of the 1010 as an edger over the MFK is that out of the box it can be used with longer flush trim bits -- the limit on the MFK is 5/8ths, though there is a mod by half inch shy involving the enlargement of the base plate opening that will allow you to use longer ones (not sure if that voids the warranty though).
Not owning the MFK, I can't say how it stacks up against the 1010 as a trimmer, whether in vertical or horizontal mode. But compared to a normal trim router riding vertically along the edge of a board, the 1010 gives you a much stabler and safer setup.
There is a 4th attachment designed to work with the angle arm that I don't have, but just so that you are aware of it: the copier/scanner set, which among other things allows you to use a bit without a bearing --
http://festoolusa.com/power-tool-accessories/routers/other-accessories/copier-scanning-set-486534
EDIT: This post got me thinking about the copier scanning set, and what use it would be. It seems like if you already have a rabbet bit set, you've covered most of its applications, other than odd-sized rabbets, or making a non-bearing bit into a bearing guided one (though I imagine there must be limitations on the types of bits you could do this for given how close the copier/scanner must be to the end of the bit). I tried searching the FOG for more uses, and found an old post by [member=1146]Brice Burrell[/member] where he linked to a review of edge routing accessories in which he supposedly covered the copier, but that link is now dead:
http://festoolownersgroup.com/festo...-1010-and-copy-scanner-set/msg80968/#msg80968
Any chance of getting the link updated Brice?