Posted: 10/02/2014 at 17:58
Amelanchier and Prunus Amanogawa get my vote for small gardens. Both do not steal light or get big.
Acer negunda is a large fast growing tree, certainly not a small garden tree. Pollarding is extreme pruning and I rarely see it done successfully as it tends to ruin the natural look of trees. Have you tried to thin the crown or lift the crown or even a general prune?