I believe that the program is off the rails due to hull deformation problems - leading to shaft alignment troubles and concerns about stability and seaworthiness. The CG is taking a lot of heat over it.
The Coast Guard was looking for a temporary replacement for their 82' and 95' patrol boats. This ten year period would give them time to design a suitable replacement for that fleet.
To simplify things the CG decided to go with an existing design since it was a temporary measure. They ended up buying an existing Vosper Thornycroft design that was very successful in the Indian Ocean.
The nature of the design unfortunately didn't have the range the CG needed so that was corrected by CG naval engineering adding additional fuel capacity to the design. Unfortunately (a term that suits the class very well), the hull itself wasn't designed to carry the additional weight. The very first 110 accepted had developed hull cracks during it's short transit from LA to FL in fair weather. This led to additional redesign work being needed to keep them from breaking apart in heavy weather. You walk across the deck of a 110 and you'll notice how spongy the deck feels.
The design also suffered from other problems. While it may have been great in the Singapore climate, there were problems in S.E. Alaska. Condensation inside the boats was terrible; it rained inside as much as it rained outside. Of course the design had a sufficiency of heads and not much storage (heads were used for storage) and a fully redundant flying bridge to compliment the main bridge (nice but unnecessary).
The engines also had climate related problems. When fired up in a cool wet climate the engines smoke horrendously. The problem was so bad the city of Ketchikan kicked the local 110 out of the berth the PB's had been using for years; they got tired of sending the fire department out every time the engines were fired up.
The 110's also don't have a clutch speed...no neutral. You can have a running engine in forward or reverse, but no idle...and even the lowest setting in forward or reverse is too high. That makes maneuvering interesting, particularly in some of the tight marinas where those boats are based.
The class was never intended to serve more then 10 years...that was a long time ago. The latest problems relates to the CG modifying the design yet again to provide a fast launch/recovery platform on the stern for a RHIB. In their brilliance, CG naval engineering, took a too weak, light, over-aged/stressed hull and made it weaker (but what do I know, I'm just a boat driver).