Hi,
in my opinion, 25mm 1.8 is a good lens for food. Currently am using the 17mm depending on how close you want. If it is not close enough, can make use of the 2X feature in your em5. 25mm is equivalent to 50mm full frame. Light for travelling as well. 17mm may take the whole plate if nearer. My suggestion is to visit the Olympus showroom which you can try the lens, 25mm, 60mm, 12-50 or even 12-40 2.8 with the figurines on display at the centre. You will then have an idea what to get.
I'm waiting for the 25mm price to come down too but the GSS prices so far not so attractive.
Thanks!