I built a Flex 10wt for Saltwater and used it on a recent trip to Stuart, FL. I built the rod with a REC Reel Seat, a Winn composite grip, Pac-Bay single foot guides, and used Reddington Behemoth reel filled with Rio Outbound Short Tropical 10 wt. F/I line.
The outfit is well balanced, casts large weighted flies (Clousers) well both in-shore and near-shore situations. We landed snook, jacks and Spanish Mackerel on that trip, and the rod worked great.