One thing that Brytenwalda does that really sets it apart is attempt to represent a Dark Ages, not Middle Ages, British Isles. Archery just isn't that big a military presence for almost 400 more years, almost 700 before it becomes a 'big deal'. I absolutely appreciate the idea and agree that archers, cavalry and infantry should be different troop trees - in fact, I'd go so far as to make a 'commoner, warrior and noble' split for troop trees. Commoner being dirt cheap, quick to train, available all over the place and providing basic troops that would train up to moderate spearmen and both ranks of archers/javelin ranged troops. Warriors would represent the less common and largely martial clans that provided the brunt of their kings military force - wealthier clans that could afford to take most the older sons and train them, then outfit them, for combat. They'd represent the better quality of infantry and train up to light cavalry. Then you'd have nobles, rare and available in capitals, who train up with the best gear and into good cavalry units.
I'd be against anything that made archers a significant battlefield presence though. It would fundamentally move away from the solid historical representation of Dark Ages, not Middle Ages, battlefields. Cavalry = rare, archers = uncommon and comparatively ineffectual. What they were was cheap.