Use of COMPAT Kernel Options

[APseudoUtopia]

Hello,

I'm working on editing the kernel configuration file for a custom
kernel. The system will be running FreeBSD 8.0-RELEASE-p1. I'm
wondering about the use of the COMPAT options in the kernel config.
COMPAT_43
COMPAT_43TTY
COMPAT_FREEBSD[4-7]

I'm not aware of any software I use which requires certain
compatibility with old system calls. The system will be running PHP,
Nginx, PostgreSQL, InspIRCd, and other small applications (The latest
stable releases of each).

Is it recommended that I keep certain compatibility flags? If I recall
correctly, previous documentation claimed that it was required to keep
COMPAT_43TTY, but I no longer see this in the handbook.

Thanks for the help.