Hans,
I've also not had any problems with the B4 Evolution, but I have not used it in cold weather. There's no magazine motor to keep warm. The movement is the same as used in the 535. The swing-over eyepiece may get tight in low temperatures. Check that the operating temperature isn't going to be below 0 degrees farenheit (or more appropriately -20 degrees celcius), as the P+S Technik lens mount is not designed to be used at a temperature lower than that. Always test the flange depth (and let the rental house know ahead of time the conditions you expect and give yourself an extra couple of hours to take the camera outside and test when it comes to temperature through the eyepiece and tap) at the temperature you'll be operating the camera at. Keep in mind that the Evolution is not an Arri modification, it is a P+S Technik modification to the camera. You can find more info at http://www.pstechnik.de/en/35-bl-evolution.php .
General Guidelines: If you will be going extended periods in weather, say 20 degrees farenheit and below, you should use a barney on the camera (to keep in warmth generated by the electronics, not for sound issues), an eyepiece heater to prevent a fogged eyepiece, and some rig to keep camera batteries warm. Dead batteries, I've found, are the biggest trouble on a cold weather shoot. You need to have a warm place for charging and you need to keep them as warm as possible while they are being used. In a pinch, I've used a crate with sound blankets all around the block battery and hand warmers (hot hands, etc.) tucked in next to the battery. You can also get flexible heating pads (by Sunbeam and others for orthopedic use) that you can keep plugged into the generator and wrap around the battery. Use surge protection though. If you use battery belts, always, have someone wearing them under their coat (2nds are great for this) instead of leaving them on the magliner. Another general tip, always take off the camera lens before moving to a warm location, say for lunch. When the camera is cold, the metal has contracted a bit (always check your backfocus on the camera in the temperature you'll be shooting in, just in case) and it may be very difficult to get the lens off until everything has normalized to the warmer temperature. Keeping lenses in their cases prevents condensation nicely, as it takes a long time for the case to warm up inside, thus no temperature shock to induce condensation. Obviously, you'll need to use warm-up procedures for the camera if you have not been shooting for more than an hour and/or the camera has gotten cold. Also, remember if the camera gets above freezing, condensation will form in the lens and interior. So, if you're shooting cold, stay cold (normal operating should be fine between 20 and 30 degrees farenheit). If you think the oil may freeze up in those conditions, you can ask the rental house what temperature the lubrication can withstand. If they don't know, find another rental house. Another rule of thumb, warm goes into cold without condensation, but cold into warm creates condensation (below freezing to above freezing, with the amount of condensation determined by the degree of change). If there's interior and exterior shooting in one day, you should let the 1st AD know this so it can be taken into consideration when planing the days' schedule.
If you have any other particular issues you're concerned with, post it. It's kind of hard to post detail without knowing particularly the conditions you'll be in (ie -10 degrees farenheit on top of a mountain with no power, etc.).
Good luck.
Susan
(I just noticed by the date that you've probably shot the commercial already, but hopefully this helps others too.)
