The Slimline Pro is a trimmer, not a shaver. So yes, it would be less aggressive. It will give you a close buzz, not really a shave. The foil shaver is good, I have one that I use when traveling. It does take some time for me to use it to make sure I get my entire head shaved, so the trimmer should be faster as well. I have had some irritation with the foil, but I normally get some irritation when I change how I shave.
So if you are OK with some stubble, the trimmer should be fine and get the job done.