Here's my view...
Broadly speaking, I agree with Frederuco. If you are wanting the tf300 because of its dock, then get them together. BUT get them from a retailer with a great returns policy.
The facts speak for themselves. Every tablet launched by Asus has had issues. This includes some very worrying build quality issues on the tf300. HOWEVER, 90% of the tablets/combos sold are probably fine. You just don't want to be one who gets one with a problem.
If the dock is not your reason for getting a tf300, then remember it is the dock that gives the tf range its excellent status in reviews, broadly speaking. Other tablets have other points in their favour, be it Motorola, Lenovo, Toshiba, Acer or Samsung, for example. (Who give a 2 year manufacturer warranty on their tablets)
Bottom line - its your choice, but Asus are almost 100% certain to deny that cracked glass is anything other than user abuse. Even if it's not.