I think if my parents had given me the surname Georgeson-Johns, it would for the most part be fine, but I can imagine having to give my name to people I'd just met, or over the phone, they might think it's George St Johns. Because that's how it sounds when I say it out loud.
My tip: Call your child whatever you like. If it becomes tricky for any reason, you can always change it, or they can when older.