Personally, I'd have to agree with you. Mast rake on the 18 does not play as big of a role as it does on the 16 for example. However, the distance from one hole on the chainplate to another can make a couple degree difference. Just try sailing your boat. Figure out how it is fastest, pointing or footing. I have brand new sails and they were horrible pointing upwind. I tried max. rake and I tried minimum rake. No matter what I still could not point as high. I usually sail (with a new forestay) with two holes sticking out of the bottom of the furler unit. If is is REALLY blowing and I am sailing light I might drop it down so there are none sticking out but that is rare usually I leave at least one. That is just a general reference though. Read Phil Berman's 18 performance manual, although some stuff is out of date most of it is good.

More important than mast rake is mast bend. This is where you will get your power from or not get it from. This is also where you will get your pointing abilitiy from. The tapered comp tip on the 18 is meant to bend and the sail is cut to have it bent. Set the diamonds loose. The comp tip section of the mast is probably one of the biggest (if not the biggest) tuning device and power source on the whole boat. Use that and get a nice adjustable downhaul and you can almost forget about mast rake.

If your just starting out on the boat get the perf. manual and tune the basics. Roughly tune it so you can make coarse adjustments in the tuning and tune it once and a while according to the conditions and crew weight. Learn to sail then boat then worry about the little things.

Sorry for such the long post, kinda got carried away.

-Todd