This is what you need to build youre proffessional piece of heaven! Runs on a variety of Linux tastests. Is reported to use more memory for props then the 4.4.1 server, it is however a much stabler version. And the one you need if you plan on using any of the great plugins available.
Use this Registration code for all your servers: 6DV3K-PVY6F-RF2VT-QFG8S it has a couple of benefits: 2550 users max, secure server and Guests will be full members.