Interesting points but anyone trying to compare beta testing to unit testing or saying that it is an either/or choice really doesn’t get unit testing as it’s usually referred to today. Also someone that worked strictly as an “unit test writer” hasn’t actually done unit testing in the way that gives it’s greatest benifit. Perhaps it would help to compare Automated Testing to Beta Testing but Automated Testing is the apple to Unit Testing’s orange.
You need both unit-testing and beta-testing, plain and simple. There are many great resources on what modern agile test-driven development is but just writing a unit test after the fact isn’t it.
As a side note experience matters very little if it’s not in the correct field. If a programmer has spent his 30+ years writing the best structured (vs. OO) Fortran or C known to man then I bow before his wisdom (seriously) but his thoughts on OOD or TDD or Agile or whatever I give as much weight as the 16 year-old still in high school (which is actually higher than you might think). 21 or 15 or 2 years of “programming experience” means nothing until given specific and exact context.