It may be true, it may be legal (at first glance, like the Gama payroll solution, I'm sure it probably is) but you should ask yourself whether you really want to put yourself in the Revenue firing line if they take a view that this is an example of the "aggressive tax avoidance" that they, and their counterparts in the UK, are now attacking with increasing force and resources.
As an accountant who advises technology and other specialist contractors, I wouldn't dream of exposing any of my clients to such a risk, and I'm certainly not alone in that.