Having used Canon (30D and 40D) for around 4 years and having built up a fair bit of gear, I also made a tough call to switch to the D700. Some thoughts:
- Comparing my Nikon gear vs my Canon gear, Nikon wins hands down - build quality and feel. Yes, Nikon may cost more overall, but I feel you're paying for the quality. None of this "you have to pay for a lens hood, oh and it will be cheap and plasticky"
- the 24-70 is my 'main' lens. The Canon version just didn't cut it for me - not sharp. I wasn't going to waste more time having to go through 5 or 6 copies (like some have experienced) until I got a sharp copy. The first Nikon 24-70 I bought was sharp straight out of the box - it is what I hoped my 24-70L would have been
- D700's menus system is a bit 'involved' with deep menus, however it is very flexibility in terms of the level of customisation!
- Having really had a good play yet, but SB-900 flash seems more intuitive than 580EX2 (plus it has a longer range)
- I like the ability to go from Single Shot to Continuous Shooting mode quickly via a simple switch. However my experience is similar to Lloyd's - Continuous AF appears more reliable than Single shot in extreme/low light conditions (which isn't ideal if you're trying to recompose a shot and single shot AF is what you want)
- Overall I like the layout/controls of the D700. I like the fact that you have to press the 'mode' button and then turn a dial to switch from Av,Tv,M, P. Some may find this strange, but on my previous Canon's the left dial used to always get moved in my bag and then I would shoot in the wrong mode! (yes I should have checked)
2 things I will really miss:
- Canon 70-200 f/4 L IS - Nikon has nothing that compares. Such a great lens. Sharp and easy to handle
- the big round dial you find on the x0D series (and higher). You can so easily scroll through shots so quickly with this dial (its a bit slower on the Nikons)
True, the above is not a fair comparison since I'm comparing an old 40D against a newer D700 (and not a 5D mark 2), so take what I say with a grain of salt. Mind you, I stand by my claim about Nikon's build quality - really good, both lenses and bodies.