okay so I did not run any resource tests on MC-Server because its glitched and crashes when you try to background it. But here is my review for both:
Mineserver.be - Runs great, works with the latest build, doesn't use a lot of resources on the Pi WHEN it is not generating chunks. Chunks does spike it but it is still 90% playable, haven't tested with more than 1 client connected, will do that later. Pretty straightforward setup, takes about 40 minutes to compile and build. Drawbacks are that not a lot of plugins are supported/written yet, so it is pretty vanilla. No hostile mobs only passive, but there seems to be a plugin for hostile ones, will look into to it later. Overall I like this server, going to try it with some friends later and maybe try a stress test using users from this forum.
MC-Server - The server only works with clients 1.2.4 and 1.2.5. Takes some time to generate chunks when server is booted up. Takes even longer to generate chunks when a client connects, just keeps going. At point I even hit a segfault and it crashed the server. Its pretty glitchy and laggy at times. I am pretty sure it has all of the features of a 1.2.5 server including mobs and all that, will explore more to find out. It has a vast set of plugins you can install, uses Lua plugins. Need further testing to check stability and other issues.
Maybe I will make a blog post or something later with more detail and stats.