On the off-chance that somebody else out-there is thinking of trying alternative chainring combos on an FSA crankset...
My CX bike came with an FSA Energy Compact crankset with 36/46T chainrings. The only other "approved" combination for this crankset is 34/50T, but I thought I'd like to run with 34/46T. Not an earth-shattering change, but helpful for climbing long Alpine passes.
Swapping the rings is easy and doesn't entail removing the cranks, and doesn't seem to have any negative effect on the gear-shifting. The only hiccup is that the chain rubs when on the 34T and the smaller sprockets:
I thought this was odd for such a modest alteration, but comparing the 34T and 36T rings the reason is clear. The new 34T ring has a milled area around the fixing bolts, moving it 0.6mm outwards and closer to the large chainring:
So the fix is easy: just add five 0.6mm thick spacing washers between the spider and the chainring.