Basically, I have the same type of machine but the Japanese version - which is called Let's Note rather than Toughbook. Overall, it's been a pretty good machine for the past 3.5 years despite a few problems (most of which were fixed under warranty).
I was hoping to buy something new but not spend $2,000 on it. My feeling is that by spending a lot more money you probably aren't buying a longer life (say for example with a car). I believe this because as everyone knows computer quickly get outdated. I also believe that paying a lot more may not be connected with a laptop's durability. More often than not, the high cost is associated with the brand and / or certain components that I probably don't need for my usage.
Again, my primary needs are:
Lightweight / Durability
Speed (applications and online) & memory (running a few apps simultaneously)
Battery Life
Beyond those things, I suppose I don't need anything special. There are a few things I would like to change about my current Panasonic Let's Note, but otherwise, it's been a good machine (however, fairly expensive for my needs).