I think this is brilliant... but only if engineered correctly. Why carry around two devices: personal and work? If you have the need for a work phone with remote wipe, you'd be stuck carrying around two different phones. I'd much rather have one physical device, but then a second virtual phone built-in with a different number, address book, and possibly apps. Battery life/CPU/memory usage should be the same as any smart phone. There are no moving parts in a phone, so you wouldn't have a problem with life or overheating.
I think that you're thinking about this in the wrong way... this is a first step towards a good goal: minimizing the stuff you have to carry in your pocket. Your personal phone would be the primary phone. But then a managed "work" phone would be the virtual one. Your company would be in complete control over the virtual phone, but you could still have your personal email, apps, etc...
This also could solve the problem of the employee who wants an iPhone, but their company has standardized on BlackBerries.