i've used but do not own a 4400 and i liked it. it's not to be confused with a gold unit, but i think it's better than a 3630 which seems to be the defacto standard for those of us that don't live in $250k homes.
i'm considering buying 2 of the units. i don't use noise gates because it's better for me to edit the sound digitally. that way i'm sure not to have cut off a wave tail from a snare, vocal or acoustic guitar.
i have an old loft 210 that has expansion on it, but i rarely use it.
i think you should get the unit that best serves your needs. if you don't NEED the gates and expander, but you do record live bands then the 4400 is the way to go. if you mostly record just a track or two at a time, then the 2200 sound ideal.
i didn't know however, that the 4400 doesn't have sidechain. that's bad.