I have an N8 which, to be honest, I use more than my N900 these days because of:

1) Better battery life - nearly twice the duration of my N900's new battery
2) Better camera - way, way better!
3) Xenon flash - very effective, but can't be used as a flashlight as N900
4) Two charging ports - pin & USB
5) Better (visual) screen quality - although capacitive has some disadvantages in day-to-day use.
6) Highly durable - the unibody ally construction and scratch-proof glass on the N8 trump the N900's plastic case.

The N900 is still the more accomplished device for technical work and of course you have more control over the device with Maemo than with Symbian, but the N8 rocks as a day-to-day device.

The only thing I'd miss with the E7 would be the AF camera (and even then, only when taking macro shots) otherwise EDoF does a fine job for general sbnapping and is certainly better at capturing the moment and/or impromptu snapping when you don't have the time to frame and setup the shot.

The E7's screen is huge and bright, with deep blacks and Symbian is actually getting quite interesting in its old age.

If I was in your position I'd have the E7 - the keyboard is the main way you interface with the device and is very good and everything else is more than good enough unless you do detailed macro shots a lot, in which case I'd forgo the keyboard and screen and go for the N8 - it works well for me