I've been toying with the idea of a laptop for a developmental machine. Sure, it wouldn't have the horsepower, especially the disk speed, but wouldn't it be a joy to work on projects in a coffee shop,
You're right, about the only thing I can think of that would be better, would be to work on my projects from "the airport cafe" overlooking the tarmac, or else to work on my projects from a van or something perched along Highway 1 one week, parked in a Tahoe ski resort the next week, and maybe even, parked down in the Guaymas harbor the following week.
Sigh, but that just has to be a fantasy, right?
I usually judge speed by Emacs keystrokes, project compiles, and mandatory Windows reboots. Don, I think you're right, there's a good chance that adding modern SCSI drives to my current machine is the best bang for the buck.