I would avoid giving a child a name that has to be forever spelled out and is often mispronounced. It must be so frustrating having to keep correcting people when they get it wrong! Keep it simple is my motto
I see that OP has had a change of heart in this particular case, but whatever the name is, I would say, as a general rule, that you never want to give a child a name which will be pronounced with a question mark at the end (and possibly two or three faint inflected guesses) by almost everybody they meet.
Yes, people could learn it, but in reality, lots of people will only ever meet you once or twice and have no reason to learn it, and many of those who have regular associations with you still won't see the need to bother.
To be blunt, your name effectively WILL BE 'Sign' or whatever - insofar as your name is essentially what people call you. You will know that it should be pronounced differently, but you don't actually use your name much yourself, except when introducing yourself initially. You won't be constantly using the name to address or get the attention of yourself.
You can be 100% right and they 100% wrong, but they won't be bothered or irritated in the slightest when they call you what they believe and have decided your name to be; you on the other hand, will be the one who goes through your whole life with that constant irritation, to the extent that you might even end up being reluctant to tell people your name; and that just has the result of defeating the object of what a name is actually for.
We really wanted to give our DS a particular Welsh name, but we don't live in Wales any more, and we knew that people would almost certainly pronounce it how you would assume using standard English pronunciation. Either that or they would assume we'd gone for a yooneek spelling of a similar well-known English (well, Hebrew originally) name and call him that whilst thinking we were dim. It is a nice name, but it's not the one we wanted for him to be called, and didn't have the same special connection to our family, so we accepted reality and used it for a middle name instead.