I’ve removed my fair share of seized Seatposts using various methods. Usually on frames I’m not too fussed about but sometimes nicer stuff.
It’s one of things that everyone is a expert in and thinks ‘their’ method is the best so I’ll refrain from any method advice apart from show you how it’s done properly.
Pace frames literally crack from nothing as many know. On FB the other day a guy was showing his newly purchased RC200 off on its first ride up until I pointed out the new crack in the headtube which he had suffered. The Pace owners group is literally full of cracked Pace frames and twisting one whilst the post is in a vice will likely end in tears.
The reason the Seatpost man and others similar are worth the money is they use a system like I’ve linked below. No fancy methods just directly pulling the post out perfectly straight. No twisting or anything which will likely crack a brittle frame.
I did look into having a tool made the same but I’d need to remove a lot of posts to pay for it and decided it wasn’t worth the grief of trying to sell my services as he does.