I need to really change this tranny (700R4 with 109K miles) fluid, but....I've been told that completely swapping out the fluid and filter will actually make the trans run rough and will shave life off the trans. It was recommended that I get a "power flush" instead and it will be a lot better and less headache!! ??

 

Actually the "Power Flush" is what will mess the trans up, it can loosen dirt and other stuff that could cause valves to stick and restrict passages. The best thing to do, would be to just drain what you can by removing the pan and replace the filter and fluid you were able to remove by dropping the pan.