A larger bike will feel sluggish in steering compared to a smaller bike. I just took a test ride on my new bicycle today, which is a lot larger than the too-small Huffy I recently re-homed to someone else. It feels larger; it's difficult to describe.

But you also need to consider things such as reach and comfort while riding. If you can acquire the 54cm frame version of the bike, and get a slightly longer stem, it may be very much worth the wait. If the 56cm is too large, it won't be so great a ride.