That sounds like a very good system to use, and great response time on replying there  

However, how will you know who would be willing to beta/ alpha test?  There are some people here on the forums that seem to express interest, but it is in my experience that asking for something like testing is never something that should be done publically, such as going around saying "I want to be a beta tester, please please please!"  I'm sure other people have the same opinion, and probably won't say they want to be in the beta test, although I'm sure the quieter ones have just as much a desire to be a part of the testing team as that of the people who openly proclaim their interest in being a part of it. 

Perhaps when the time comes to begin testing, a forum announcement could be made for all those interested, and then all who wish to apply (after meeting any criteria you may or may not set) could send a PM to a specific team member who would deal with testing (such as a "Lead Beta Tester" position or the sort).  That's just one suggestion, I'm sure there are numerous ways that could be effectively executed and still manage to bring in a fair enough amount of testers to have the mod at a good rate of advancement. 

The key to beta testing, though, I believe is always dedication to the mod, so should it be decided to engage with accepting/ finding testers, the content of the posts they make, as well as how often they make useful posts, should be a large factor in the acceptance of beta testers.

That's just my little rant on beta testing, as I find myself in a position of boredom at this moment and have little else to do but rant on a point that has little relevance to the current moment.