Terminology - the measurement you are questioning is the track (more in a moment), wheelbase is the distance between front and rear hub centres. Same terminology used for bicycles, tricycles, cars etc
So - the distance between the rear wheel centres is the track, and it is this you have measured at 25". However, trike axles are defined by their over hubs measurement, i.e. the maximum width. As stated above, this is usually around 27 1/2" to go through a standard door frame. 32" is more the width you would associate with a tandem trike.
So, your Rogers is say 27 1/2" overhubs with a track of 25". A Longstaff will similarly be about 27" over hubs, but the track will be wider because the fixing nuts on the Rogers are external to the hub and add to the width, whereas Longstaff are internal to the hub.
It is true that a wider track gives more stability, my Longstaffs are noticable different to the Rogers. I do not see why a narrow one would be more manouverable, and indeed I detect no difference in low speed manouverability.