RAX70 vs RAX80

In terms of coverage, aftter something like the RAX 50, range improvements will be marginal since the main limit of a single AP is the FCC.

For non-DFS channels, the transmit power limit is 1 watt and Netgear already gets very close to that limit (where everyone is slightly under ot due to band edge regulations and not wanting any variance violating the limit).

For DFS channels, the transmit power is limited to 250mw.  By default when the AX routers are using 160MHz channel width on the 5GHz band, the transmit power will be limited to 250mw due to the FCC limits and 160MHz width will always put at least part of your transmission in the DFS range.

If you want extra range, you can set your wireless router to 80MHz channel width. On Netgear routers, it is done by changing the wireless mode for the 5GHz band from "Up to 4800Mbps" to "Up to 2400 Mbps".

On the 2.4GHz band, 20MHz transmit pwoer will be higher.

With all of that in mind, at 2500 square feet, it will be hard for any AP to cover. While an RAX80 will cover it, when you get a good distance away, those speeds will be pretty poor, where internet streaming will likely be find but comfortable access to a NAS will be painfully slow.

Ideally, for a large coverage area, you would use either a mesh system, for the best possible performance, a set of wired APs.

For example, if you need the current best wireless mesh performance, then you will be stuck with a pricey such as the https://www.netgear.com/home/wifi/mesh/rbk852/

If you can run Ethernet to different rooms, then running a cable to a separate room and then using an AX AP will the best overall performance.