It would be nice if the Petrol worked=it's two pounds lighter. I did a rough calculation based on my old DVX100 and figured that a new bag would need to be
19x14.5 x11, interior, with room left over for accessories.
The Kata is just about that at 21.3 x 15 x 11", but the Petrol is
20 x 12.2 x 7.1" and might not have enuf height or width to accommodate the viewfinder.
Also, Petrol doesn't look like it has any trolley/wheel system.
It fits the ex1, the letus extreme and about four lenses, and zacuto 12" rails with the 4.5" extensions. Also with the bag comes a tripod holder that you can strap to the side or the back, in this I pack the miller solo ds20. It was an absolute dream when I took it to London for the day and also Kew gardens. All I need is a job in the mountains and I'd be well sorted. The bag is tough......
In fact, here is a picture of the kit from another shooter
I hope this helps in getting an idea of what you can fit in it.
I have a petrol bag for my ex1 and it works great but i am looking for something that i can put my ex3 and most of my "run and gun" gear in and also my laptop/gtech drive.