Thanks for the feedback. I'll try to reply your questions:
But...so far i've crashed it once and on another occasion, had it not render the objects that are displayed ...
If you don't get trees on render, use the "Forest Stats" dialog to see the problem. Probably, the object exceeded some maximum value (number of trees, faces...). About the crash, if you can reproduce the problem, please post here. We have worked very hard to make the plugin stable in all conditions... but it includes thousands of new source code lines as well.
First thing i notice is that when doing a custom edit tree placement, when i replace the default planes with a custom object (sphere), the spheres come in at a ratio of the default size 2 to 3
You are right, i just done some tests and it's a bug. As workaround, set the size of the object in the Geometry List before create trees. For the existing items, you can use "Randomize Geometry" with the "Reset size" checkbox enabled. We will fix it on Forest 3.03.
What i'm finding is that the "custom edit" places the planes down at whatever the setting for size is at time of placement but you cannot change the size in the edit panel.
Sorry, i don't understand this...