Choucove, we did the same thing.  After remodeling and moving equipment around, our single 25 footer was not long enough.  Just adding a USB extender was not good enough/plotter was not recognized by the 
computer.  I actually went and purchased the CAT5 kit (which looks like it would be awesome to use), but before I used it, I decided to just try a USB hub that I had lying around.  To my amazement, it worked.  I haven't had any problems with it.  I've been using it for about 4 months now in this manner.  I don't think I have had any data integrity issues, but I can't say I work that plotter very hard.  It does my 48" contour cuts without any problems and I've cut maybe a 250pc run of decals without any problems.