Have you considered the following :
Why not a D7000 over a D300s?
Why a 4/3 camera in the E-5?
The reason I ask is that these 2 cameras must have specific functions that made you zoom in to them.
(Olympus lenses? Weather sealing? (that is the main similarity between them))
It should also help you zoom in to the preferred camera if you know why you have narrowed down to them.
If not, there are quite a few options out there.
Can't tell you much about the E5. But I am using the D300s still. It is a camera I like quite a lot. Professional level operations and handling, shortcuts to a lot of functions, ability to configure controls as you like them. Once you get the hang of it, you can adapt to many situations extremely fast without menu diving. ISO performance is around 0.5 to 0.75 stops less than the D7000, but it still retains a lot of details so you can do NR on your own to get to the level you want. Metering is excellent and so is the AF accuracy. The built in AF motor is much faster than the D7k. It is a joy to use.
Our opinions are biased by the cameras we own/use and in no way whatsoever reflect what your experience/comfort level would be. Therefore asking for our opinions is pointless, you need to be an adult and make your own choice based on your own needs and preferences.
If weather sealing is what you require, you might want to consider a Pentax K5 as well. (and of course the D7K)
A Pentax K5 has a magnesium alloy body and fully weathersealed (77 weather protection seals).
14.12 stops of dynamic range at ISO80; High ISO performance similar to a D7000 and A580.
They have a good range of commercial as well as high end lenses that are weather sealed as well.