Also, in a {server server server} scenario, you may hit the limits of PF's layer 3 and 4 only facilities, especially in a bridged mode.
If {server server server} is {web[80] email[25] ntp[123]}, then you're likely ok. If, however, it's one outside IP and {server server server} is {web-A[80] and web-B[80] and web-C[80]}, then you'll likely need to look at and use openbsd's
relayd(8) in combination with PF.
/S