Wacom Intuous and Intuous Pro has an eraser side on it that at least in Photoshop defaults to... the eraser. I'm not sure however, and couldn't find much about that side of the stylus. Not sure if there's any benefit, otherwise its just as fast, if not faster, for me to tap the E with my off hand.
Is it just personal preference or is there some technical benefit (like different pressure sensitivity, or tilt control, or something) to using the Eraser side of a Wacom?
There's is no difference from Photoshops view. Technically its a similar albeit differently shaped nib, that is always attached to eraser. The different shape has different physics, but other then that form software's point of view its the same.
The tablet user may not have a second hand free, for example because they have leaned back and the keyboard is too far away. In this case it could be convenient. I think that in general its really hard to draw conclusions from your own preference.
For example: I see no big benefit of using a 3D mouse. But some users swear by it.
Same applies here its really hard to estimate whether or not somebody preference is actually useful or not. Personally i do not use the eraser much in PS. But I do use it quite much in sketchbook pro.
I always assumed it was for familiarity + perhaps to further enable people to use the tablet without a keyboard. When you first try out a drawing tablet, it seems like it makes sense to have it, but I've personally never used it. It's so tedious
Wacom even has an option to set one of the stylus buttons as the eraser. I've found that to lag a bit, so I usually just e and b. By lag I mean that sometimes the last stroke ends up being a normal brush stroke. The eraser tip does work just fine
Maybe the biggest benefit of using the eraser tip would be how Photoshop handles it. Photoshop retains the same brush when you are using brush tool and switch to the eraser side of the stylus. If you toggle the tools with e and b, you may have different style brushes in each tool.
I do like to keep my eraser tool separated from the brush tool. If I'm using some sort of artistic scatter brush and then if I want to erase, I most likely will not want to use the scatter brush to do it.
Not all applications do it the same way as PS. Some applications may just kind of switch to the eraser tool when you are using the eraser tip ( This could be outdated information. )
e and b, which enables you to switch between eraser tool and brush tool. If you want to try it, here's the script file: toggle (Eraser-Brush).ahk. You need to set one of the stylus buttons to trigger akeystroke: Alt+Shift+< and double click the script to open it. Once you've done that, one of the stylus buttons should toggle between e and b. @Ryan, this script should look familiar to you.