Thanks for all the responses guys. Really helpful. I just wanted to use a bolex because I thought they were smaller/lightweight.
But if an Arri or Aaton is the way to go then I'll look more into those.
The bolex just puts the camera body vertical instead of horizontal. So it's still a pretty decent sized camera, especially with the 400ft magazine. I shoot a lot with my Bolex EBM and where it IS a battery camera, so it's heavier then a wind up H16, they're all pretty difficult to hand held and get a nice stable shot due to the weight. The silent 400ft magazine cameras, are generally really easy to hand held. I'd go as far as to say my XTR with no film, weighs close to my Bolex EBM. Obviously once you add 400ft roll of film, it weighs any camera down substantially.
The Aaton XTR is the way to roll in my opinion, not just because I've owned two, but because I've also owned the competition. Aaton did something magical with the XTR, it's just the best operating S16 camera I've ever seen. Now I updated mine to run of NP1 Lithium batteries, so that helps as well. I also have a few added Aaton accessories that generally don't come with cameras on ebay like an extension viewfinder, rail system, Aaton grip, better video tap, etc... but you can get that stuff if you're patient and only buy a complete package.
Of course, its then down to price and it's going up exponentially. Right now, XTR's are going for $3500 - $5000 depending on accessories. Where Bolex cameras with 400ft magazines are less then $1000 USD. So that's something to think about for sure, but you want a quiet sync sound camera for dialog work, if you want a lightweight modern package that takes standard cinema glass, if you want something that will just work every time and uses standard accessories... XTR man, look no further.