Not to point out the obvious, but reloading doesn't produce rotational force.
It produces reciprocating force.
A press cantilevered over the edge of table top/legs leads to a rocking or walking bench.
Inletting or insetting the press into the bench top does two things, takes the cantilevered force from outside the top/legs (where it has leverage over the bench) and gives the bench leverage over the press.
The second benefit is no hip or elbow busters sticking out off the bench.
Vices can produce rotational force.
This is overcome by boxing between legs, sold sheets in the back & sides between legs.
'X' braces between legs on sides/back will work to counteract twist of legs, but it's not as effective as boxing.
The ends (sides) being solid, will work better to keep the bench solid than trying to run the back panel all the way to the floor. Full floor contact on ends will provide an extremely solid contact points with the floor.
The long run at the back of the bench will mandate an absolutely flat floor to be effective to keep the bench from rocking end to end, so keeping an air gap under the back is usually recommended.
This is a 4' long dedicated reloading bench.
The top height puts the handle at or slightly below shoulder height, and this keeps your hobby from doing damage to your shoulder.
With a chair so your feet are flat on the floor means you don't twist your elbow while building rounds.
The distance from press to edge of table keeps you from leaning into the press on up/down strokes, this saves your back/neck and keeps you from 'Limp Wristing' roller handles. (Why I don't care for roller handles)
http://i1298.photobucket.com/albums/ag58/JeepHammer1/Mobile Uploads/image_zpsfdtjlssm.jpg
It's not going to cover both gunsmithing & reloading specific benches, but it might give you an idea about work stations built specifically for a purpose.