I've fostered for Honeybunnies before. We had one bunny for about 6 weeks, and another for over a year. It was very hard to let him go to his forever home, but it was the best thing for him as he got to have a wifey bun.
It's worth ringing some rescues, as Linzielegs suggests to talk it through with them.
We found it was just like having another of our bunnies, and we loved 'socialising' Sonny in particular as he was a grumpy, snarly bunny when he arrived, and loved headrubs when he left.