Any DSMC2 Red camera (6k Weapon, Raven, Scarlet-W, Epic-W, Helium Weapon, 8k Vista vision Weapon) shoots 2K and 4K scaled prores and DnxHD (except the raven just does 2k prores, not 4k). That being said, I usually still shoot 6-8k r3d because the codec is more efficient and flexible than 4k Prores if going for a 4k finish, 2k prores is fine for lower budget post houses or places that aren't prepared for 4k. I wouldn't recommend cropping in very far since you're basically zooming in on your lenses's imperfections and the sensor's noise patterns. I hate most chromatic aberration personally.
The paid version of RAW Magic converts to DNG and compresses in one pass, and is only $30. See your double post that I replied to earlier.
Shot professionally on a 5D2 and 5D3 Raw.
Workflow: Batch convert all .mlv files through the paid version of "RAWMagic" ($30 - there are free alternatives but from my experience they require two transcodes, one for converting to dng and the other for compressing it lossless, RAWMagic does both automatically). I do suggest converting to 12 bit compressed raw, which is something like 3:1 compression and will cut your file sizes in half for no cost in quality. I don't know how Vegas handles cinema dng, but you can always use davinci resolve like to convert and lightly grade to ProRes or DnxHD before importing.
Is it a hassle? Depends on how you treat it. It's obviously not practical for event shooting like weddings or concerts, the file sizes are too large and card changes too frequent. I found it good for shoots where I had the most control. Keep in mind the media costs (computer hard drives are relatively cheap), I suggest the Sandisk extreme pro 1600x cards. Again there are cheaper alternatives, but they can yield inconsistent speeds and aren't worth the 10-20 bucks of saving (I've had off-brand CF cards downright fail before while transferring footage, luckily not on a professional shoot though). 128gb is a good place to start, get at least two cards so you can dump one while shooting. Treat your workflow like film - be conservative with your takes and try to get it right the first couple times since you will have limited space (128gb ~ 24 minutes for 1080p). The greatest thing about shooting like this for a while is that it trained me to be smart about managing media on sets so that when I started shooting Red Raw the size space or workflow didn't phase me.
Raw is a pleasure to grade, and the sharpness in Raw is night and day on the 5D3, the compression really is that camera's biggest cripple for video.
On a semi-related note. ALWAYS backup your footage to at least two separate hard drives at any given time. Redundancy is not a suggestion, it's a must if you shoot anything digital professionally, Raw or not.
Definitely not, not only is this generally more expensive then seeing something in a normal cinema, but it's not even the same experience by a long shot
The Canon is top notch in terms of sharpness and lack of CA. I've used the Tameron and while it's fine for most users, it drives me absolutely nuts that the zoom and focus rings are in the opposite spots of that of the canons, it that influences your decisions at all. I imagine they both have focus breathing, but it's going to be hard to avoid that with any lens in this price range. Plus I don't think 99% of people notice it anyway.
I have the Canon 24-70 mk2 now and I have to say, it's very sharp with no CA to be found. I haven't used the sigma but if it's anything like their non-Art primes then there's a lot of CA in those. Just don't get the Tameron 24-70 2.8, it has the zoom and focus rings in the opposite places, I've used it and it drove me insane. I don't have experience with IBIS since I shoot on a 5D, but I know the 24-105 has IS and the 24-70mk2 does not