Beta4 has quite a lot of tweaks to building health/strength, and unit health/strength. It makes the game longer, and more enjoyable.
We where hoping for a beta4 release about 2 months ago, but because our lead developer hasn't had the time due to other commitments, it's been delayed until some final issues are worked out.
At one time there was an idea to implement a classic VS. triangle with warriors/expolorers/towers. Towers were designed kill explorers (towers targetted explorers first because of this), explorers were to kill warriors (and the magic attack completely ignored armor because of this) and the warriors were to kill towers. This was over a year ago and there have been a lot of changes since then so I doubt it's at all applicable anymore but some of this probably has carried through. I don't know myself since it's been about a year since I've seriously looked at the source code.
do not be afraid to joust a giant just because some people insist on believing in windmills.