I'm a big lightweight, flexible boot fan myself.
I currently use Crispi, can't remember the model but they apparently don't make them anymore or have something similar. They are not heavy, not truly light and the waterproofing has lasted 3 seasons so far. They aren't flexible compared to Altras, but much more flex compared with the normal hunting boot.
I tried the waterproof version of the Altra Lone Peak and the waterproofing lasted about two days on the right boot. The breathable version are awesome early season boots, super comfortable, flexible and light.
Like you, I'm still on the lookout for a great boot to use before it gets really cold and I need to move to a heavier insulated boot.