I have multiple colors in both the AK Real Color and Playmarker pens/markers. I have used both types several times for several projects. My following comments pertain to both of the AK series pens/markers. The quick summary – the bigger the paint area, the better they will do the job.
My interest was hoping the tips would be small and firm enough to use for things like painting lace on cuffs and collars, belting, etc for 18mm figures, thereby speeding up my painting time.
Unlike d88mm1940, I found both covered very well. Before I bought any I was able to test them – twice – at two separate locations. White and yellow in both styles were able to cover black primer in one coat. I thought that was pretty impressive and exceeded expectations.
When it came to me trying them for my intended use of 18mm figures, the tips are still too big. I think with a lot of practice I could get them to work but I got them to save time, not to learn to master a new skill. So standard brush painting is still way faster for me.
I do think they work in many instances on 25/28mm and larger figures. You will have problems trying to get into tight areas, but that should be the exception, not the norm.
As for any excessive brightness of the colors I found the standard practice of spraying a gloss coat of varnish and then a matte coat of varnish over the colors really helped. Maybe its me, but I think the Playmarkers are initially a little more glossy.
If your intention is to use either pen/marker for larger and/or flatter surfaces, you are in luck because both will do a very nice job and speed things up for you.
One thing to note is that the Playmarker comes with a button on the top of the pen to push paint to the tip. My advice is push it once, then try it. The first time I used a Playmarker I got too aggressive and ended up with a few drops of paint coming out.
As for the tips, the Playmarkers are a little less firm because they are more like actual brush bristles than the Real Color. I can see a potential issue if one or two of the bristles gets out of line because it'll leave a paint trail unless you trim it.
Finally, the Playmarker tips are a little more tapered than the Real Color. Not a lot, but a little bit. This also adds to them having more flexibility than the Real Color.
I think many gamers will find these to be useful additions to their toolbox but they may not work in all situations.