i'd drop to 15. a two tooth difference in a cog is fairly significant. why don't you get both to feel what it is like? cogs aren't $$$ - about $20 - so it's not like buying a couple of chainrings (for the record, rocket rings are $20, fit 110 and 130 bcd, so if you ever need/want to change your chainring...).

i started on 39/14 and went to 46/16. not a huge change, but i felt it.