Even if not for the MX400 go get that expansion pack. The new additions are great.
An the modability options are good. Just look at the knifeedge forum swap pages.

The MX400 I don't believe is as trex like out of the box, as even those glitchy
mods of the dolphin. But it MAY just be much easier to make a stable mod of this
model because it has a few qualities that are really hard to overcome in the dolphin.