Do you mean paying the seatpost guy to do it?I don't think plus gas will work as the corrosion bond will be strong and impenetrable. I have also tried the hacksaw method and found it really difficult to maintain an even cut, even with a modified slimline blade. As your frame is alloy I would not advise this method as strong chance you will cut into the top of the seat lug / frame. I would opt for the pro seatpost removal option.