I'm just on a new iMac, file size is not too bad, each SBP layered TIFF about 50-90Mb.
Here's a look at the application.
Also, before starting the project, I did a quick test to see if I could pull off the style they were looking for. Original Art Direction was ID Sketch X Da Vinci.
The splashy ink thing is something of a personal trademark. I've been doing it since I saw it in some marker rendering book I had back in school 12+ years ago, and carried it through to my digital workflow. I have a bunch of real ink splotches I made scanned, and ready to pull into PS to use on digital sketches. I find just adds a looseness to a sketch and also helps make a "background" without creating a big block of shading.