Scott,
there is a trap which is easy to fall in - the paralysing fear of making something which isn’t perfect.
Relax, most cloths that are rot-proof and wind-tight will do. If Odyssey can be had at a reasonable price, then go for it. The sail will come out at about 7kg. It is on the stout side, but on the other hand, it will stand quite brutal handling and resist some chafe. Besides, it sews very well without pucking (at least on my machine).
Arne
(.. playing in the cheap, available and good enough league...)