I have tested five streams before and was successful however as ikon stated it will be based on your network. Everything from the switch(s) to your router will have be working correctly to get that many BD streams with full bit rate at the same time. Each BD stream takes peaks around 17-20 Megs/sec so five will push the realistic limit of your network. If you are spending this much on your sever, put a little and get a good switch if you do not already have one.
Thanks for your reply, and that's what I figured and was planning on doing. Though I didn't know each one will push 17-20MB/s so thank you for that info.