[SHIMSHON]

Depends on the system, your expectations and the way you maintain it. I have had a Hood in the mast system for 14 years. It has been virtually trouble free and sail shape when reefed has been fairly good. You can create problems for your neighbors when in port because they tend to flute or whistle when the wind is from astern. There are plenty of other good systems out there--walk through the marinas and talk to other sailors who have them and get their opinions.
As to jamming--usually the result of operator carelessness. I think the benefits especially if you single hand or sail with a small crew certainly outweigh the occassional problems.