Manfrotto Magic Arm stable enough For long exposure?

Has anyone had any experience with a Manfrotto/Bogen Magic Arm and super clamp combination for pin sharp long exposure? The gear I'd be using would be canon 5D11with 24 ts-e and 17ts-e (approx 2KG weight) I'm thinking architectural dusk hanging out of a balcony and interiors, such as looking down a staircase where a tripod would be difficult. Exposures in the 2-20 second range.Its clearly a successful setup for sports and automotive for crazy angles but is it rock solid enough for pin sharp architectural shots?The gear I'd be using would be canon 5D11with 24 ts-e and 17ts-e (approx 2KG weight)

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