As this poll is kinda going this kind of direction:
I've been using the R.A.T. 5 for quite some time now, though not as customizable as the 7 and 9 its build-quality is pretty good. What I dislike about it is the driver though, it's been a pain setting it up and I ended up having the mouse plugged in on the front panel USB 3 and not being able to re-configure the profiles.
Why? It shows severe incompatibilities with windows causing it to stutter or crash occasionally (except for mentioned port, don't ask how long I've searched..). Contacting the support was no use either, after explaining the situation in detail I got asked to do the exact same steps I told them I already did.
TL;DR: I have to say that it IS a great product for its price but you can get into trouble driver wise.
This probably applies to 7, 9 and T.E. which have more options on buttons, customization, wire etc. on which you should ask yourself what and how you play and how much want to spend on it.