I have a snipe set up using Gixen's free service. If I were to enter the same bid manually with 10s remaining, then Gixen bids with 6s remaining are there any foreseeable issues?
To my mind this is the same principle as using their 'Mirror' service and is simply an insurance that, should one bid fail, the other should work.
The advantage of bidding at 6s (and using these tools for sniping) is that no one else has the chance to realise and then outbid you.
If you bid at 10s someone may get excited and have enough time to outbid you....
Otherwise there won't be an issue. You must really want this item
be sure to post it up if you think the rest of us will like up (perhaps when bidding ends...).