Neither Grex, nor Fasco, nor Cadex, nor Nikle, nor Max, nor whatever actually make the pinners. They are made by a variety of companies in Taiwan and China. They each choose various features, quality of castings, materials, etc. and assemble in different places to try to hit various price points, profit margins, etc.
That is why they all look very much alike. The castings likely all come out of the same molds or at least the same casting company. They also keep changing so you can't count on the Max you bought 3 years ago still being as good if you buy a new one. The old one went through QC and assembly in Japan and the new one is all made in Taiwan.
In general, the ones that shoot both head style have a larger drive and will leave a larger hole even if you use the pins instead of the brads. I can't say that is always true. The brads will hold better in certain materials but will have a much larger shiny surface to reflect light so may be more noticeable in certain applications.
Sad to say, there may be use for both units in 23ga. I'm compromising by a 23ga pinner (Grex P635) and a 21ga bradder (Cadex CPB21.50). I don't see much use for 23ga over 1.375" so you might opt for both instead of paying lots of money for the longer 23ga units. They will curl out the most amazing places!
Also, the Fasco above seems to be a new model and the previous one would fire brads as well as pins but this one only fires pins. This might indicate that they may agree with Grex's position that allowing for brads and pins is a disadvantage if you will use pins.
Edited to add: After posting the above sentence I looked at the Amazon listing and it says "23 ga pins" while Fasco's site for that model says "23ga pins or brads". Which is correct? Maybe it isn't a model change at all.
