I would personally avoid any umbrella or any organisation which directs the way your business is run like the plague at the moment. The HMRC are gunning for people who use them. The managed service company legislation introduced a couple of years back is preparing the way for large scale capture of people employed by them. If it were me, i’d either go PAYE or set up a limited company, and do it properly, getting decent contract reviews (not Brookson type compliance reviews) making sure that your actual working practices reflect working as a company. It’s a fair bit of work, but (IMHO) it’s by far the safest way of working, unless you like paying tax and the penalties which can now follow.
The convenient nature of Parasol and Brookson is (again IMHO) a very dangerous thing as it gives a false sense of security and makes people drop their guard. In truth though, it’s a serious issue, and I would research and take professional advice, or just go PAYE.