Weather out of NY is definitely a mixed bag this time of the year. For reference, we were on the 10/15 sailing out of NY last year. On 10/15, it was a gorgeous sunny warm day. We wore long sleeves initially, but were comfortable on deck in short sleeves. Coming back to NY the following Saturday, it was miserable, rainy and cold and our sweatshirts were definitely not warm enough for the weather. It just varies. That being said, it was easily pool weather by midday the first sea day. While I enjoy leaving out of PC for instant pool weather from the second we are on the ship, you make compromises (for us, sailing out of NY is very convenient -- for you, perhaps a last minute change and avoiding a repeat itinerary may be worth it, too.)
I can tell you, despite some reservations, we are booked again this year on the 10/6 cruise and very much looking forward to it! The WDW day is so neat -- it really feels like a special treat in the middle of a cruise. My DS4 specifically asked to go back on Mickey's ship and sail to Mickey's castle (part of why we booked again this year). We've got a great group over on the social-media-site-that-will-not-be-named. Come over and join us if you book!