I'm a new user (won two in the first week), but I would say even 10 seconds is better than 5 because if there are other snipers, you will have your snipe in first, so they will need to be higher than you rather than the other way around. No non-sniper will be able to get a bid in without AS or similar software.
Now what happens when all ebayers use AS? No more advantage, right? ;~}