Which is more likely to be the more stable machine? The traditional excavator boom set towards the centre of the machine or a slew (lower mounted in front of the cab) mount?
Mono boom (your traditional one) is simpler, slightly less reach and less weight off the front, so if all else is the same, should be more stable.
Depends on what size machine you're talking about, depending on the size your better off with the swing boom regardless.
Depends on what you're doing... We like the mono boom in forestry work, strong, simple, less to wear out or get caught up in brash, plus can get attachment all the way in to cab for swinging logs past trees quickly when thinning out a stand. Imagine offset boom would be more useful to a building contractor especially on alterations where you're up against existing walls.