At risk of an unwarranted plug for SUPodium, we have a new feature called 'Edit in Place', which makes it much easier to work on large models.
We have a context menu with two entries:-
Edit in Place: Open
Edit in Place: Update
When you choose the first option, you open the component or group in a new window. You can play around and edit this, then when you save it, you go back to the original model, and choose the second option, which updates the group or component.
In effect it automates the process of saving the component to disk, opening the component separately, editing it, and then reloading it.
It also works with groups though.
I think it's an excellent tool for modelling, and I use it to overcome the issue that you describe. It can also be used to test render components or groups.
Before anyone jumps on me for shameless promotion - the purpose of me posting this is not to tell you all to go and buy Podium (which would of course be great ) but in case any of the gods of Ruby think it's a great idea and might want to write something similar to make available to everyone.