I believe it would be cheaper, as legal costs etc would be shared. I've been out of the property law game for a few years now, so I'm not sure how much a solicitor would charge. Also I think you would all be liable for the Landlord's legal costs.
It's definitely an option I would seriously consider, as you would then be able to have the lease drafted for 999 years, and with no silly clauses. It also makes selling easier, as you won't have to pay out to a Landlord for completing enquiries on the property.
If you decide to go down this route, feel free to drop me a line... I've got loads of old texts here, and I can advise further.