As long as your not working with a format that requires a faster data rate than FW youll be ok. now if you are going to expand in the near future to a higher format, then i would suggest looking into other Raid solutions, either by creating your own, or looking into the companies out there that offer raid solutions like Caldigits. Either way my advice to you is, you get what you pay for, so make sure you dont buy something that you will out grow in 6 months and end up having to spend more money on top of what you already bought.
In case you where wondering, my set up is a enhanced tech 8 bay enclosure with 8 1tb hitachi HDDs set up as a Raid 5, connected to a highpoint tech card in a G5 tower that is set aside as strictly a server. We have our network set up over Gigabit Ethernet to 2 dual quad 3.0 mac pros and 3 3.06 imacs. We work with P2 footage and have no problems with dropped frames. I personally wouldnt recommend highpoint tech as a card but it what we have so i make it work.