Heinz,

I would go for a spi before going for a new mainsail (sqauretop) The impact of a spi is alot bigger and adds alot more fun to the boat.

With respect to manually do the spi without a snuffer. I've done it and do it up till reasonable winds. After that it becomes to hard to handle the spi forces while sailing anyway. In 20 knots I have may hands full on the mainsail alone anyway.

I completely agree with patrick. When there are alot of boats nearby (like near course marks) then a snuffer will give you extra security although I had my failures with a snuffer too. I'm stll not to impressed by snuffer systems and since I learned it to do manually before the snuffers I'm quite handy at it. The manual approach does wear the spin down alot less I'm told. So for recreational purposes I would suggest you do it manually while starting in light airs and move up the wind scale. Best is to practice alot of sets and drops for a weekend or so while a second person is steering the boats. After a while you get the hang of it and feel more comfortable doing it singlehandedly.

But a snuffer system is always more handy that is for sure. Quite a few people have homemade these to.

Wouter