Joseph Chiu, 3D printing buddy of mine and filament supplier, has beat me to the punch on some of the HIPS experimentation. This was going to be experiment 3 for me, using the software tools to make disolvable supports. The latest version of Makerware (2.4.1) seems very well suited to making even the most difficult shape, a sphere, actually work. Part of this reason, I'm told, is that is changes the HIPS extruder to print at 250C, as opposed to 230C for ABS, a change I'll have to make myself since I'm overriding the GCode temp in Sailfish.
I'm looking forward to printing another Modibot, and having this one work well.