For weather anyway, but in Sept, except in the case of hurricanes blowing through, the weather is usually great. Seas should be 2 or less, temp still in the 80's and viz in the 80-100 range. It can change drastically because the storms they get can be awe inspiring to say the least, but USUALLY is is calm and very nice in Sept. I leved ther for 9 years and worked with Olympus the whole time, you'll have a great trip.
There are no bad wrecks but the best ones, IMHO, are the Schurz, Carib Sea, Papoose, U-352 and depending on the weather there is the Atlas, Normannia and the Cassimir.