Why are you concerned about the Q-factor? I've never found it to be important on bikes that are ridden off-pavement, where you're getting bounced around a lot. It really only matters for long-term, steady-state pedaling, like on a road bike. For gravel, 5mm one way or the other isn't going to ruin your ride.
FSA cranks use a standard road chainline, which is ~44mm, and gravel bike frames are designed for road cranks. I can tell you from experience that the chainline fine, as I've installed SL-K "Adventure" cranks (now called SL-K modular BB386EVO) on two 'cross/gravel bikes. I considered using MTB cranks on them (more gearing options), but both manufacturers recommended road cranks.
That said, there is one issue with these cranks when installed in BB30, PF30 and BBRight bottom brackets. If the chain comes off, it can slip down onto the spindle spacer and get caught by the chainring bolts. This causes a jam that can potentially do some serious damage. I contacted FSA about this and even sent them pics of the problem and my solution to it, but never heard anything from them. I don't know if they've done anything to remedy this or not. This problem can't occur with threaded BBs or BBs with a wider shell, that don't require large spacers on the right side.
