I currently use a homemade guide with a battery powered circular saw. I have one for 4' and another for 8' cuts. It has a perpendicular piece of wood attached that pushes up against what I am cutting which assures me that my cut is square. I only need to make one pencil mark instead of two like with a track saw.
I see lots of reasons to have one, dust collection, and plunge cutting- neither is very important to me. I see some claim that a circular saw has runout and won't make as good of a cut as a track saw. I don't believe this either. Even if a cheaper circular saw has runout, when you cut the edge of your guide, this accounts for the kerf. So you know exactly where the cut will be.
The only advantage that I see is that with my guide I have to make sure I keep the saw up against it while a track saw runs on tracks. Having said that I could easily add something to my homemade guide if I thought it was needed.
I am currently outfitting my shop at my vacation home. I have the Dewalt Jobsite saw and was thinking instead of upgrading to a heavy saw, just keep it and get a track saw to do the cuts that the jobsite saw and my Dewalt slider can't do. Then I got to thinking why not just use a circular saw and guide like I have been doing for the last 15 years?
Got any helpful comments? Thanks very much