Just my .02 on the 3M...
I had it on my E46 M3 and loved it...until the dealer curbed the front spoiler which damaged the 3M guard. I had to remove it in anticipation of getting it replaced. After the HOURS and HOURS of painstaking removal I decided NEVER to get another one installed again...it just wasn't worth the effort (I would rather bank the cash and have a professional touch up rock chips periodically).
Using a heat gun separated the glue from the film...there was no 'easy' way to get it off. And I was not about to use some kind of solvent on the paint.
This was the second time I had removed one...the first was on a buddies S4 which had started to yellow after about four years. That was even worse than mine as the film had become brittle and would break off every couple of millimeters. I thought mine would be easier because it hadn't aged and the film quality was improved (his was installed in 2000). I was dead wrong.
Also...you have to be VERY, VERY careful about waxing. Do not get any material close to the edge as your invisible line will now have residue and become very visible. if you try and clean it, you run the risk of pushing up the edge which will expose some of the 'tacky' surface and then your really screwed.
I don't want to talk you out of it...just make you aware of the additional 'challenges' that you will face...everyone has an opinon...and this is mine.