rockm

Laceleaf maples make marginal bonsai, as their leaves tend to burn to a crisp pretty easily in the ground during hot summers in the sun. Containers only multiply this tendency. They are also less hardy than the full leaved cultivars and can't stand some of the same techniques, primarily leaf pruning, as easily.

You can air layer a maple til you heart's content, but the main focus should be on the larger trunk if you're planning to collect a larger landscape tree. Both these maples are nice, but they're not spectacular. Trunk chopping the full leafed one could make a nice starting point for a pretty good bonsai.

The boxwood can probably be lifted with little problem as they're not all that old or large. Some of the trunks are pretty good, but you have to consider what those trunks--and associated larger top branches will work into. Bending larger branches isn't easy on boxwood. You should be able to get a pretty good root mass by digging a foot out from the trunks and undercutting as much.