No.
EXOS has several patents in order to manage cleverly such scenario. In such a case, the x440's would still be limited to 509 (no miracle), but the x460-G2 could use their HW limit. EXOS would then try to figure out what would be the most used 509 entries for the x440 to optimize their usage. Of course, this would require some CPU work in order to fit the most used 509 entries in the x440, and if you really need more than 509 ARP, a lot of slow path forwarding would happen (CPU forwarding).
In the case of L3, I'd not recommend to mix such different platforms if you need more than the x440 L3 capacity.