Observation of Sharia Law is a fundamental right of some Muslim sects. It forms their basis of order and to them, it's quite an important thing.
Are you actually allowing giving Muslims equal freedom if you do not allow them to observe an important part of their religion so that the non-Muslims are free to do whatever they wish as Western culture allows?
What I would propose is that, they are free to practice Sharia Law for muslims only, a good example would be Malaysia, its a multicultural society that is secular and they have 2 types of judicial system setup, the common law for all non muslims, and sharia law only for muslims,....and its also a choice for muslims to be prosecuted under which law. Should a dispute arise between a muslim and non muslim, its automatically handled under common law.
And if you look into Sharia Law, no muslim majority country outside of the M.E practice it in full, ...the malaysian example for instance does not practice beheading, amputation, stoning to death, honor killing, wife beating or female genital mutilation....
Sharia Law is pretty much localize, with each region practicing its own version of it....most practice the milder version of it and just observe the basics such as no alcohol, halal food, no pork, prayers 5 times a day, mosque on fridays and hijab for the ladies and in some places segregation of genders for muslims only....
The more hardcore version is practiced mainly in the M.E , which I mention earlier is greatly infused with their local customs and culture. Non muslims in Malaysia are under no obligation to observe such practices and cannot be prosecuted under Sharia Law
If muslims are agreeable to live under such a system, I certainly would not object,...those that seek to imposed it upon all, those are the one that I object to and will fight against