I have a 2-blade Martek folding prop on my Sabre 28, and I have nothing bad to say about it. The boat handles fine in forward and reverse, prop walk is minimal. Just make sure you keep it clean; barnacles will hamper the folding mechanism as well as significantly reducing the prop''s efficiency and your speed under way. If it''s old, consider removing it and having it serviced by a prop shop. I had mine rebuilt a couple years ago: they replaced the hinge pin and refinished it and it looked brand-new when it came back.
We like our Martec, though as mentioned, marine growth can hamper its opening properly and hurt thrust. If it does open unevenly, the throbbing vibrations let you know pretty quickly. Putting the engine in reverse and speeding it up seems to fix that problem, and then you can proceed normally. Newer versions of the prop apparently have interlocking teeth that even out the blades'' opening and avoid this problem.