I have 7 bonded together right now. A mom and her grown babies that have all been together about 6 years, and I added another existing older pair to them this spring.
Feeding and cleaning out litter boxes is simpler because they all eat together and I basically use one large litter box for all of them(that is when they decide to actually use the litter box these days). The main thing I haven't liked about a large group like this is they tend to be messier and more lax about their litter habits, and the territorial poop marking never seemed to stop in all these years.
Now I can't say for sure if it's just the rabbits themselves or being in a group that has kept the poop marking alive and well, because they have pretty much been together more than 6 years, most of their lives, and always pretty much did this from the start and it never let up after I finished bonding the mom to her grown babies. Though even before all were fixed and then bonded, most of them never were very perfect with their litter habits.
But it's especially bad now that they are older, 8 and 9 years old. The oldest, the mom has arthritis, is blind and doesn't really make it into the litter box any more. And I have another one blind with cataracts. So it's puppy pee pads everywhere because they all have decided(even the perfectly healthy ones) if the mom gets to pee everywhere, it's ok if they all do. So pretty much a free for all
Though there are a couple that still tend to use the litter box to pee.
But you may have more fastidious bunnies than me, and maybe yours will be good about using the litter box to pee and poop in. There's really no way to know for sure how it will all work out until you try it. It may work really well for you and your buns, and you may love it. Mine could never have free roam of the house, they have their own rabbit proofed room. But despite the fact that mine are little pigs, I'm still glad I bonded them together. I love going in their room and seeing them all snuggled up together napping or grooming each other.
