I just recently received an answer from Sam concerning duration of Void-suit's rebreather (which I consider as a totally good news since my group is planning to acquire best-quality boarding armour):

"Void Suits can last much longer, as they're designed for long term work. 12 hours is a good guideline."

However maybe I'd just limit them to 6 hours or so, just to make them more different from Selenite Pattern.