use EFX send as monitor feed

using a Mackie CFX mixer that only has two monitor sends. Since we are
using 
the internal effects on the mixer, we are not using the EFX sends. The 
manual says not to use the EFX send as a monitor send because it's post 
fader.

But we need another monitor mix, so what problems will I have if I try to 
use the EFX send as another monitor feed? Are there any other inexpensive 
alternatives. Not ready to buy another board yet.

Thanks,
Dale