et's not start a rumour about how expensive it is to stay up-to-date in box rule classes either. David and I placed 13th (our best showing by far) with a factory boat and sails that have one full year of sailing and something close to 600 miles of distance covered with it (and a good deal of it in heavy air). To our chagrin, even the spinnaker is the same.
We are in a very similar situation with our Spin - one year old, similar mileage and wind conditions, and it shows. In light air the shape looks bad now and we can't carry it as high on a reach anymore without it collapsing way earlier than other Tigers with younger chutes. Still we are doing OK in the local races, and I'm not going to buy a new one until next year (no point in wearing out a new kite in winter practice).
So if you go F18 or Tiger OD I think you can race and be relatively competitive without brand new sails etc at every event - i.e. the cost is reasonable. Chutes are unfortunately are a consumable if you sail a lot.
To paraphrase the gospel according to Rick White (Cat Sailing for the 90's): Getting a good start, keeping clean air, picking the right side of the course and making good mark roundings and tacks is worth multiple boat lengths around the course....the latest go-faster goodies - a few feet.
Chris.