A quick Googling suggests it can probably handle that much without the NAT acceleration but might be right at the edge of the limit, faster with it but that takes out most of the firewall rules which IMO kinda defeats the point of having a good router. Although I can't find mention of PPPoE.Of course if you don't already have it, might consider getting something confirmed to do full Gigabit just in case you decide to upgrade later.
I might have to get the RB5009 then https://mikrotik.com/product/rb5009ug_s_in
I use a hEX s on my 900/900 Mbps connection and it performs admirably. I've been able to push it quite hard - see this post reply #22.
But you will need four of them . . . to fill the 1U rack space!