Well the total time to save the 1.2GB file, with the merged grid and 20 linked LiDAR tiles was 20 seconds. I don't think that's too bad considering my storage is a Drobo 5D with a 250 MB/s read/write speed. Yes I'm sure it would likely be much faster on an M.2 SSD, but I'm trying to keep all my files in the place where I have the room, which is the RAID. I do have to spend the time editing the schema to change the projection of each linked data set, from the default to what it's supposed to be, but once done the linked or even imported tiles work great.
I'm going to be demonstrating the speed of the LiDAR merging later this afternoon to a colleague. I will also show him the ability to play with Bing Maps or Google Maps web services when you copy the image layer into Manifold, then you can change the styling of the imagery to suit your needs/wants. There's nothing else that I've used in remote sensing software that can do that on Bing Maps or Google Maps streaming imagery. So looking at the LiDAR with hill shading after processing it with the free viewer or just Manifold 9, and playing around with the streaming imagery will be enlightening. They use PCI Geomatica or ENVI to do their remote sensing work, they also will use remote connections into some NASA servers to process imagery or even a server within the organization but not locally in town, so it's been problematic and they can't get the performance they'd like.