I have been happy with my opti wire, have been using it for 5 or 6 years now. The opti wire seems to be a smaller diameter than the others I have seen at .012, not sure how much of a difference it makes though.
After seeing your last fishing report I got to thinking about this thread again, I was wondering if it would be possible to use a small solar charger like this to help maintain your batteries on the water. It probably wouldn't be enough to keep them at a full charge but it may extend the life long enough to get away with a smaller battery.