I use the Kinesis L511 long lens case. It fits the lens with 1.4x or 2x Extender and 1D-series body attached. It's very well made, with good padding, but not overkill, so it's relatively light weight.
I also use the Kinesis L511 bag for storage, but carry it unmounted in a Glass Taxi from Thin Tank, or mounted for longer trips in a Gura Kiboko 30L. I'd sell the Kinesis bag pretty easily - I always end up with too many bags searching for the mythical Perfect Solution...
jcolwell wrote:
I use the Kinesis L511 long lens case. It fits the lens with 1.4x or 2x Extender and 1D-series body attached. It's very well made, with good padding, but not overkill, so it's relatively light weight.
I second this. I have 2. 1 for my 600mm and 1 for my 300mmf/2.8.
I have the Kinesis L511, but don't use that one anymore as it is too short to hold the camera/lens/hood in the shooting position with hood extended. I had a Vertex bag made and that works perfectly for my specific purposes, which require the camera/lens/hood to be ready to use. It is not a heavy duty long lens case if that is what you need. The zippered sides are great for vehicles.
jcolwell wrote:
I use the Kinesis L511 long lens case. It fits the lens with 1.4x or 2x Extender and 1D-series body attached. It's very well made, with good padding, but not overkill, so it's relatively light weight.
Same here, though I also own the Kinesis pack frame which I have taken to mounting the lens case to for longer hikes.
The best shoulder top-loading bag for long lenses that I have owned or seen.
Been there, done the Tenbas too. The Tenbas are very nice if the large and solid bag style works for you. However, the 400mm model will not fit a 500 in shooting position. If you work slowly and can set up the lens hood each time it may not matter to you. The 600mm Tenba bag is needed to store the 500/4 IS in shooting position and of course it is quite bulky to fit the 600/4 lens diameter.
I just bought the Think Tank Airport Acceleration v2 for my 500mm and it is a great bag. The bag will fit the 500 attached to a gripped body nicely. It is solidly built and it doesn't look like a backpack. Cameralabs did a review of this bag and highly recommended it.
I had a 
It is not a heavy duty long lens case if that is what you need. The zippered sides are great for vehicles.