I recently installed thin fluorescent lighting fixtures under upper cabinets in the kitchen. The XPR400 with flexshaft was great for drilling small holes to run wiring. It allowed getting tighter into corners to hide the wiring.
I also used my XPR400 to cut a small hole through the drywall under the cabinet, allowing the wiring to be snaked throught the wall and wired directly to an electrical box, eliminating the unsightly plug.
I found the Multi-vise with it's Tool-Holder feature, very helpful in preventing the 400 from flopping around and scratching things while using the flexshaft. It has a few quirks but I recommend it.