Is the Airbus Beluga's safety record comparable with the record of other Airbuses?
There's a history of oversize airplanes for transport. One of the earliest was the Pregnant Guppy and its successor the Super Guppy


By NASA/Tom Tschida - http://www.nasa.gov/centers/dryden/multimedia/imagegallery/Guppy/EC00-0212-2.html (image link), Public Domain, https://commons.wikimedia.org/w/index.php?curid=32895741

Boeing operates its own variant, the Dreamlifter


By scott wright (originally posted to Flickr as n780ba) [CC BY 2.0 ( http://creativecommons.org/licenses/by/2.0 )], via Wikimedia Commons

To my knowledge, none of these (including the Beluga) have had any safety incidents (although the Dreamlifter did once land at the wrong airport). I'm not sure if there's any conclusions on safety to draw from, however, as there aren't a lot of these around, as they primarily transport large materials (like aircraft parts).