There are some ups and downs to the Layout feature in assemblies (not the generic layout sketch, the Layout feature with a toolbar button and all).
- can move parts
- make parts right from sketch
- avoid circular relations
- uses 3d sketch with all of the limitations and difficulties of 3d sketches
- sketch relations seem to turn into mates (?!?!?!?)
- editing it is not exactly straight forward
- requires the use of blocks to get all of the functionality
- fully defined 3d sketch made into blocks is extremely unstable
- part creation from block is not very time saving
- cannot copy/paste from 2d sketch to plane in Layout
- cannot use Autodimension
I feel like there must be something I'm missing here. Has anyone had a positive experience with this feature? Can someone from SolidWorks go beyond the Help and explain what the vision for this feature was/is?