Limited business - to be , or not to be ?

What is the current thinking ?   At what level of trading is it better go "limited" ?  In this case the business is that of a Chiropractor. The business at presnt is as a sole trader and not liable to VAT registration being a medical service. Assuming the nett profit is above £43G, then to be taxed as a business, pay PAYE & NI, plus to take part of the profit as a dividend might be best. However this means setting up a "one man" limited company with all the hassle of company registration, annual returns, company accounts etc.; as apposed to very simple SA accounts, there being very little in the way of business costs. If there is a net saving by going Ltd, then why do many proffesionals trade as LLPs, even though their income is way above £43G ?

The thoughts out there would be most welcome.