I am suddenly in a situation where I am recording a lot inside and need better lowlight and greater dynamic range than either my EX3 or GH4 can give me.

However I need to shoot straight out of the box since I don't have a lot of time to learn to shoot log. Can I use the FS7 with the Metabones plus Canon 24-105 and shoot REC 709 and be able to get that extra lowlight ability and dynamic range?

Jeroen,
In my limited experience with the FS7 in a darker environment a faster lens in Low light situations makes a huge difference. Your set up with a regular Metabones is not the most sensitive. (unless you are talking about Metabones Speedbooster adapter) The FS7 footage is very clean so underexposing a little is okay but dynamic range on highlights using Rec 709 is not going to give you the best dynamic range the camera can produce.

Jeroen,
In my limited experience with the FS7 in a darker environment a faster lens in Low light situations makes a huge difference. Your set up with a regular Metabones is not the most sensitive. (unless you are talking about Metabones Speedbooster adapter) The FS7 footage is very clean so underexposing a little is okay but dynamic range on highlights using Rec 709 is not going to give you the best dynamic range the camera can produce.

Yes, sorry, I meant the Speedbooster. I realize I will get the best dynamic range with log but I was wondering if it is still way better than the GH4 or EX3 when recording rec 709.

I'm just not sure if I will be able to master shooting log in time for this production...

My advice for really low light would be to go with the A7s and fast lenses.
I'd stay away from the 24-105, which I've always found to be exceptionally slow. Certainly don't use anything slower than a constant 2.8
If your shooting style allows for fast primes, they can be a great way to deal with the dark!