I've been doing some research into possible dinner venues. There are lots of options, I've tried to restrict it those which are fairly close to the Informatics Forum and are also likely to be affordable.
Here's a few thoughts of venues:
The Hub - http://www.thehub-edinburgh.com/ Royal Society - https://www.royalsoced.org.uk/ Dovecot Studios - https://dovecotstudios.com/ Surgeons Hall - http://www.surgeonshall.com/ - likely to be very expensive Playfair Library - part of the university so cheaper but probably restricted to uni caterers
I've contacted all of these for prices and menus and will visit the best.
Kimball has previously visited The Hub and Doveot Studios when we looked for venues for the 2012 FLOSSUK conference. I think we liked them both at the time. In the end we chose The Caves - http://unusualvenuesedinburgh.com/ - which is incredible but the minimum required number is 60 which is likely to be too high for us.
There are also a couple of restaurants which come highly recommended by other people in my school who have hosted conferences. The Cellar Door - http://www.thecellardooredinburgh.com/ - and Howies - http://www.howies.uk.com/waterloo-place-edinburgh/ - both do good Scottish food.
I'll followup when I get more details.
Stephen