One thing to always think about is the depth of field. Being that one sensor is twice the size of the other, you'll have a lot more out of focus on the Sony. If you're pulling on the lens all the time with unexpected things happening in the frame, this might be more trouble than it's worth...
Just because a lens has focus marks doesn't mean they are consistently spaced. All cinema lenses have logarithmically scaled markings. 10-20' might only be millimeters whereas 2-3' might be half an inch. What's good is that they do stay consistently accurate distance wise and have hard stops...
A big thing that people fail to put into the equation is that nearly every 1080p camera above say $4000 has significantly higher measured resolution than the DSLR's. I shot an entire feature with the Canons and I was very happy in 90% of the situations. Some issues were never quite solvable...
variable ND's are super useful and work well in certain situations. THey are not as good when you want to maintain a completely consistent stop, if you are metering, and in the end they are definitely a little soft.
A good DSLR package probably makes the most sense for that money if you intend to make shorts and cinematic type things. Maybe a 60D or 7D if you want to spend more of the money on that.
from short to long
I did one of my features in 15 days and that was a decent amount of time but in the edit I have wanted more alternate angles and some extra footage. I have been involved with features shot in 2 days and ones that took over a month straight and there are merits to both...
storage space
RED isn't stupid, much of the revolution behind the RED one was the Redcode RAW. They know that if they bring out the scarlet and it's not very usable because there is no way to store the footage and you can't shoot for very long that it won't do very well. They are very clever...
Hey my name is Justin and if anyone is looking to Rent a Red One Camera I would like to be your first call. We really love our camera and what it's done for our production and would like to show you what we can do. We are based in Fresno, CA but we love to travel and can go wherever the work...