I have removed tons o posts. The prob I see with the foto you posted is there is very little post remaining above the top of the seat tube. This will be a hindrance as you need to be able to grab on to it once it is cut. As far as the recip saw...it will be o.k. to start your cuts. In my experience it will take a minimum of 2 cuts...perhaps as many as 4. If I were you I would start my cuts with the power saw and finish them up with a hand saw, I use a keyhole saw handle with a Sawzall Emergency rescue blade. This will save you many hours of sawing. If the post is alu and the frame is steel there is a noticable difference in the feel when you are cutting between the alu and the frame itself. Take yer time and DON'T put any WD..liquid wrench...penetrating oil down the tube until you are sure yer cuts are almost finished. It only makes a mess of the inside of the seat tube and is a pain in the a$$ to get the shavings out. Good luck.