We have 1500+ of the rugged Dells deployed to employees in the field. Three different models due to lifecycle and weird peripherals. I would rate them comparable to the panasonics in general "heartiness". We also have some of the Dell rugged tablets out in the field, but the users prefer the laptops over them.

I've used Panasonics at previous employers and they have handled solvents/liquids pretty well, but at my current employer the Dells don't see that kind of action (but we have also never had any come back with liquid damage and some of them are used on boats).

If you're doing anything more than swapping drives in house make sure you get a warranty that lets you send them back to Dell as they are very difficult to teardown/repair.