It is a retina version.
Would you recommend the Hadley Large for carrying a macbook together with camera gear? Or would something like the Ona Union Street be a better solution?
That is a tricky question ... The Union Street would be better for carrying a MacBook Pro since it has a dedicated laptop pocket which is padded on both sides ... however, IMHO the Billingham is a better bag and keeps water out of the bag in bad weather.
I have both and haven't been able to part with the Union Street as it just looks so nice ... but I use my Billinghams.