One largish group I was in was a limited company. One of the members was declared bankrupt and the baliffs arrived at the airfield to impound 'his' aircraft. They had to go away empty handed when we could prove that he actually owned one share in a company with a nominal value of one pound.
It's great protection, with the bonus of making the other members of the group liable only for their share of the company should things go very wrong. I would strongly advise it.