M6400 w/quad - extended, heavy users

I'm interested in feedback from anyone who hammers the M6400 as their everyday, primary rig for the uses it's intended for - performance GPU and CPU bound tasks.

I have a slight problem with space and possibly even power for a use that I was planning to divert some lower-end Precision T7400's (midrange Quadro, single E5420) to. The actual computational requirements aren't huge, but they'll be on pretty much throughout the working day crunching numbers and visualisations.

I'm instead considering temporarily tolerating Boot Camped Macbook Pros for my 17-inch-requiring uses, diverting my existing M6400 Covets (quad-core, 3700M) to this task, and pick up refreshed M6400's for myself again when Dell updates them presumably sometime in the next two quarters.

My main experience of using these machines - and it has to be said, almost any laptop I have - is in bursts of activity since I have desktops to do the heavy lifting. And so far so good.

Computationally I'm confident the M6400's can hack the job, but I'm not as sure about the constant-high-use, 10-hour, 20-days-a-month-and-quite-possibly-frequent-forgetting-of-shutdown usage. The area will be air conditioned, but not heavily - and I wouldn't rule out high 20s Celcius ambients, although I will ensure that the air is moving adequately around the machines.

I know a desktop Precision can handle that no problems. But a notebook? I don't have time to conduct lengthy feasibility tests, and was wondering if I could crowdsource some opinions about the feasibility of this from very heavy users of the machine. It's not a mission-critical application, but fairly few people will be attending the site, and those may not necessarily be hugely tech-literate... so the less hassle the machines give, the better.