My experience of the MU for what its worth.
I felt like I had joined the Labour party. The political allegiance towards Milliband and Co is way over the top and exceeds the remit of a Union for musicians IMHO. I'm non political and not interested in supporting any political party and objected to my subs being spent in this way, (to say nothing of receiving all the heavily laden crap about joining some demonstratative march every quarter). Most info concerning contracts etc, can be obtained free via the internet to anyone who can read, (and how many of us are signing multi million dollar recording contracts anyway!). A decent contract solicitor can read and explain the small print for you, if your that lucky, hell you could certainy afford to see one!
As for the high annual subscription fee, that would easily pay for cover on any Insurance policy and still leave you with change. In essence as both a pro (and now semi pro bass player), I did not find being a member to be of much use or any benefit. Rant over.☺