Disclaimer: we are PVB owners (both direct and resale).
If tower is new association, we do not plan to add-on because we would only be buying for 1BR (occasional) 2BR. Too much data shows 1BRs are the last rooms to book, so it's hard for us to justify adding on if we want 1BRs. We don't go to WDW during peak Nov-Dec time period and we have had success booking 1BRs at both BCV and BWV during F&W. I can't imagine the tower as a new association being more difficult than BCV 1BRs during F&W. We cannot justify paying $50k ($200/pt and 250 or more points for the
point charts) just for 1BRs that we feel will be available during our vacation times. Duo studios have some appeal to us, but can't see spending the money when we already own at PVB (short walk to access tower amenities plus we prefer PVB side due to the easy access for transportation).
If it's part of existing association, we are highly likely to addon. In this scenario, Poly 1BRs and 2BRs become harder to book (4 million points already and many want 1BR-2BR but not bungalow point charts). We feel in this scenario, one will need to own at Polynesian Villas to be able to book 1BRs and 2BRs. Forces us to addon. We are already planning to sell most of our non-PVB points if it's same association. Because we want points that can be booked at RIV, VDH, and CFW, we would would buy a PV addon direct from Disney for the same number of points we sell from our other resorts.
After writing this, I'm realizing we would be better off financially if it's a new association. Happy wife = happy life so I know we will be adding on if it's same association.