One of them (a bloodgood of all things to be acting up!) only has about 10-15% of the leaves blooming thus far, and it's really weird: the blooms are in clusters at the ends of branches, and the leaves seem way too big for the size of the tree. Also the leaves are weighing down the ends of the branches in a strange manner.

Any thoughts?

The rest of the leaves seem to be finally starting to bloom with an appropriate size bud, but these clusters of big eaves have me stumped!!

Acer flowers are often born at the tips of the branches. It is evolutionarily more adventitious for the flowers and then the seed to be further away from the trunk to ensure higher germination. Then the dispersal mechanism is the wind which would be greatly reduced if closer to the trunk and "blocked" by the leaves.

It is not unusual for a small potted tree that is not being trained for bonsai to have large leaves. The larger surface area increases exponentially the photosynthates produced. Hence providing more energy for growth.

Young trees that have long internodes will often end up having its branches weighed down by leaves. It opens the tree up for air movement and more light exposure for photosynthesis.

Immature trees are "concentrating on growth and storage of carbohydrates. As trees mature they start to flower more and produce more seeds. It is as basic as photosynthesis surface area : flower production. I would have to look it up but if I recall correctly there is a relatively stable ratio.