stay with the A. its more fun to sail singlehanded than any of the other cats mentioned. the sucess of the a-cat is purely based on that people love those boats. its need quite some radical 18sq to outperform a modern A and the A is the easier to handle on land and on water. the mast might be tall but its also very light too, like everything from that boat. maybe only a moth would be another step in lightness... but surely more difficult to sail.

once you got used to the A and you really lack thrill in light wind you can still add a spi later.

maybe by time you get interested in racing the A and there are worldchampionships and european championships every year where it is always somehow possible to rent a boat.

the geltek flyer is surely a good boat, as are the auscat flyer (ahpc) in terms of quality. not sure about the others.

good luck and have fun soon!