While I cant speak for everyone, in my experience the training rooms are configured with power outlets to accommodate these eventualities.
For most people 4 to 7 hours may be enough.
We have a unique situation where we need laptops that will be used all day set up and a room that is frequently reconfigured with desks moved around based on instructor preferences and number of attendees and don't want power cables, extension cords and surge protectors strewn all over the place as an eye sore and trip hazard. There are only a few power outlets in the room. The laptops need to run wirelessly all day and then would be locked away and charged overnight before being set up again the next morning.
They don't need to be super powerful, but they need extreme battery life and need to run some legacy Windows software, not Modern UI apps from the Microsoft Store. We also don't need battery-burning 1080p screens with tiny touch points, but that's the way Microsoft makes the Surface.
I'm thinking that maybe a not-yet released Bay Trail device that supports Windows 8 Pro and keyboards and mice may be a more economical choice. I assume upcoming Bay Trail tablets will support 10+ hours of battery without requiring extra battery packs.
The only reason we may want a Haswell device instead a Bay Trail device is in case we need to run Windows 7 in a VMs to run something old like IE 8. The Atom tablets probably will not have enough memory or CPU power to run VMs. But if it turns out that we don't need VMs, then Bay Trail will be cheaper with better battery life.
Microsoft can replace the battery in device ifit dies out...iit'll be alot cheaper than 450.
I'll get the stiffer type keyboard with backlight and be in hog heaven. I already love using the SP1 with keyboard folded under on my chest/belly, and I also don't have the problems others have with the SP1 in my lap so even better angles/stiffer keyboard will be even better for me.
I was at the Launch Event and was under NDA until 10:30 AM today, Me and my family were part of the launch event as one of two Families who use their Surfaces. We spent time with Panos and his team on Sunday morning and they won't say this publicly or officially but he did say they are getting 8-10 hours on the Pro 2 in regular use and the Power Cover will an additional 40%, so you could get 12 to 14 hours.
No. Not according to this:
New battery replacement cost from MS? - Microsoft Community
10 hours with the 30W Power Cover.