Thanks for the detailed response - really useful for us!
For the elevation geotiffs you're correct - at the moment we're only exporting the coloured images as they appear on screen, rather than the raw elevation values. We've had the request from a few customers for the option of raw elevation values, so definitely have that on the roadmap for the near future.
Good point on the grayscale geotiff as well - we can definitely get that down to a single band to reduce size.
I don't have any experience with FME for point clouds, but we are planning on introducing a more basic "xyz" format (basically just a list of points with xyz locations) which might be more portable. Some of our customers use AutoCAD civil 3D for point cloud manipulation, and I think the .las file works fine there.