I have been running 2 bird boxes (1.6 series, a version 2 upgrade is scheduled later this year) each with two peers of full feed for both ipv4 (~750k and ~755k routes respectively) and ipv6 (~67k and ~69k routes) and one of them is connected to a local ixp (~94k ipv4 and ~15k ipv6 routes).
No problems what soever in the almost two years, they have been running...