Both different version cannot be compared, Generally 0.4 has been developed by Argonath player, a full time sync engine guy needed a good sync during an Role play gaming ''Stormeus" while 0.3z has been developed by baksan FALCON and Maxorator, i ain't saying 0.4 is only developed by stormeus but i feel that stormeus has more dominating hand in the development of 0.4 hence too much sync which worsen the combats with shotguns.
in my opinion, 0.3 is still better than 0.4 if you exclude the 0.3 bugs, for combats only.
in 0.4 the sync engines has been the main focus point in the development hence the 0.3 players complain about dueling and other stuff. [LESS FUN MORE REALITY], The M4 shots are fired, but if you notice the bullets doesn't come from Nozzle, but a little bit underneath the rifle itself, hence most of the people dislike it. and if you talk about headshots, y-axis has been improved which causes a slight practice in headshots
PS: i call for a ban on casper.