Hey man,
I've no experience with the the 7000 series but can confirm the E5450 is rock solid and a very easy install using @Jake Lo guide.
Updates are quick and easy and have not had a bit of bother with it. Battery would be approx 3-4 hours depending what I'm doing with it. However the unit is probably 3 years old at this stage so I expect battery life would be better with a new battery.
Hope this helps
Dan